Oceans & Seas: Estimation Quiz About the Blue Planet

Answer: The Antarctic Desert

Antarctica is the largest desert in the world. It covers about 14 million square kilometers. Despite all the ice and cold it officially counts as a desert. The reason is very low precipitation. In some places it has barely rained or snowed for millions of years.

Answer: Pacific Ocean

The Pacific Ocean is the largest ocean in the world. It covers about 165 million square kilometers. That is more than all the land on Earth put together. Deep inside it lies the Mariana Trench, the deepest point on the planet.

Answer: 5

Earth has five oceans. They are the Pacific, Atlantic, Indian, Arctic and Southern Ocean. Together they cover more than 70 percent of the planet. The Southern Ocean was only officially recognized as the fifth one in the year 2000.

Answer: Mount Everest

Mount Everest is the tallest mountain in the world above sea level. Its peak reaches 8,849 meters and still grows a few millimeters each year. It stands in the Himalayas on the border between Nepal and China. The first confirmed climb to the top was in 1953.

Answer: 14

Oceania has 14 independent countries. Among them are Australia, New Zealand and many small island states like Fiji and Samoa. Oceania is the continent with the fewest people. Many of its islands are only a few square kilometers in size.

Answer: Mediterranean Sea

The Mediterranean Sea separates Europe and Africa. At its narrowest point, the Strait of Gibraltar, the coasts are only 14 kilometers apart. The sea covers more than two million square kilometers. For thousands of years it has been a key route for trade and travel.

Answer: Arctic Ocean

The Arctic Ocean is the smallest ocean in the world. It is about five times smaller than the Pacific and lies around the North Pole. Most of it stays covered in ice almost all year. However, climate change is making this ice melt faster and faster.

Answer: Canada

Canada has the longest coastline in the world. It measures about 202,000 kilometers. The reason is the many islands in the north of the country. If you walked along the whole coast, it would take you more than 20 years.

Answer: 37

The Simpsons have aired since 1989. Season 37 started on September 28, 2025. That makes it the longest-running animated series and the longest-running primetime scripted series in US TV history. The Fox network has already renewed the show through Season 40. Over 800 episodes have aired so far.

Answer: 8

Game of Thrones ran for eight full seasons, from 2011 to 2019. In total there are 73 episodes. The series finale was watched in more than 19 million US homes at once. Many fans, however, were not happy with how the story finally ended.

Answer: Javier Colon

Javier Colon won the first season of The Voice USA in 2011. He was on Coach Adam Levine's team. As a prize he received 100,000 dollars and a record deal. His album afterwards only reached number 134 on the charts, however.

Answer: 10

Friends ran for ten seasons, from 1994 to 2004. In total there are 236 episodes about the six friends living in New York. In the final season each main actor earned one million dollars per episode. The show is still loved and rewatched around the world today.

Answer: 5

Breaking Bad has five seasons and aired from 2008 to 2013. The show follows chemistry teacher Walter White, who turns into a drug maker. It is often called one of the best TV series ever made. Critics especially praise the acting of Bryan Cranston in the lead role.

Answer: 3 voyages

Captain James Cook sailed to the Pacific three times, from 1768 to 1779. He mapped New Zealand and the east coast of Australia. On the third trip he was killed in a fight in Hawaii. His maps were so precise that they were used for over 100 years.

Answer: around 30,000

A great white shark goes through around 30,000 teeth in its life, and some estimates run as high as 50,000. When one tooth falls out, a new one moves up right away. The teeth sit in several rows behind each other like a conveyor belt. This way the shark always has sharp tools for hunting.

Answer: 10,994

The Mariana Trench goes down to 10,994 meters. It lies in the western Pacific, east of the Philippines. Down there it is pitch black and the pressure is a thousand times higher than at the surface. Still, strange deep sea creatures live there.

Answer: 0

A shark has zero bones in its body. Its whole skeleton is made of cartilage, the same stuff as in our ears. This keeps the shark light and flexible in the water. Only its teeth contain hard, bone-like material.

Answer: 32,000

The oceans contain about 32,000 fish species. Scientists still discover new ones every year. The biggest fish is the whale shark at up to 13 meters long. The smallest fish measures just eight millimeters.

Answer: About 300,000

About 300,000 kilometers of fiber optic cable lie under the Atlantic. That is almost eight times around the Earth. Nearly all data between Europe and America flows through these cables. Sometimes sharks bite them or ship anchors damage them.

Answer: 9,000

A single fiber strand in Google's trans-Pacific cable stretches 9,000 kilometers. The cable connects the US with Japan across the Pacific Ocean. Despite the length, light travels end to end in less than a second. Cables like this carry almost all internet traffic between continents.

Answer: 82

Each NBA team plays 82 games in the regular season. Half are at home, the other half on the road. The season runs from October to April. The top 16 teams make the playoffs. From there they fight for the championship title.

Answer: 30

A blue whale can grow up to 30 meters long. That is longer than three city buses in a row. It is the largest animal that ever lived on Earth, bigger than any dinosaur. Its heart alone is the size of a small car.

Answer: ~400

A Greenland shark can live for about 400 years. That makes it the oldest vertebrate in the world. It lives deep in the icy northern seas. Its movements are extremely slow. A female only has her first offspring at around 150 years old.

Answer: ~2,000

Scientists know around 2,000 species of jellyfish. Some are tiny, while others have tentacles up to 30 meters long. Jellyfish have no brain and no heart. They have lived in the oceans for more than 500 million years, longer than dinosaurs.

Answer: 40

There are around 40 species of dolphins. Most live in the sea, but some live in rivers. The bottlenose dolphin is the most famous one from films and aquariums. The killer whale, also called orca, is the largest dolphin in the world.

Answer: 7

Seven penguin species live in Antarctica. The best known is the huge emperor penguin. There are also the Adélie, chinstrap, gentoo, king, rockhopper, and macaroni penguins. They breed on ice or rocky shores. In the freezing water, they hunt for fish and krill.

Answer: 2,700

A newborn blue whale weighs about 2,700 kilograms. That is as heavy as a small car. It is the biggest baby in the world. Every day, the calf gains around 90 kilograms. After just one year, it is twice as long as at birth.

Answer: 188

A blue whale's call can reach up to 188 decibels. That makes it louder than a jet taking off. Under water, its song travels across thousands of kilometers. This is how blue whales find each other in the vast ocean.

Answer: ~100

A sea turtle lays around 100 eggs per nest in one season. Often she returns to the beach several times during the season. In total, she can lay up to 500 eggs. Only about one in 1,000 hatchlings reaches adulthood.

Answer: Varies, up to 800

Some jellyfish have up to 800 tentacles. The number depends on the species. The lion's mane jellyfish, for example, has flowing tentacles over 30 meters long. Every tentacle is covered with tiny stinging cells. They fire venom as soon as they touch prey.

Answer: 2,000

A sperm whale dives up to 2,000 meters into the sea. That is deeper than almost any other mammal can go. Down there, it hunts giant squid in complete darkness. A single dive can last more than an hour.

Answer: 12

A dolphin is pregnant for about 12 months, so a full year. The baby is born underwater, tail first. The mother pushes it to the surface right away so it can breathe. Dolphin mothers care for their calves for several years.

Answer: 15

A dolphin can hold about 15 liters of air in its lungs. That would fill many medium-sized plastic bottles. While diving, it uses up almost all of this air. A human only uses about a quarter of the lung air with each breath.

Answer: 206 (human), 0 (shark)

A human has 206 bones, while a shark has 0. Instead, sharks have a skeleton made of cartilage, a soft supporting tissue. That keeps them light and agile in the water. Only their teeth are hard and can fossilize after death.

Answer: 190

A blue whale calf drinks about 190 liters of milk every day. That would fill a whole bathtub. The mother's milk is very fatty and rich. Thanks to this, the calf gains several kilograms in just one hour. After six months, it is already many meters longer.

Answer: 71,000

An Arctic tern flies about 71,000 kilometers every year. That is the longest migration of any animal on Earth. It travels from the Arctic to the Antarctic and back each year. Over its lifetime, it covers more distance than three trips to the moon.

Answer: 10

A dolphin leaps out of the water up to 10 times in one minute. This is called breaching. Jumping lets it move faster than swimming below the surface. Often, dolphins also leap just for fun or to call other dolphins.

Answer: About 500

About 500 shark species are known today (more precisely around 540, per the IUCN Shark Specialist Group). The smallest is the Dwarf Lanternshark at just 20 centimeters. The largest is the Whale Shark, up to 12 meters long. About a third of all shark species are threatened. The main reasons are overfishing and the shark fin trade. Over 50 new shark species have been discovered since the year 2000.

Answer: ~310 quintillion

The Atlantic holds about 310 quintillion liters of water in total. That is a 310 with 18 zeros behind it. No one can truly picture that much water at once. It is the second largest ocean in the world after the Pacific.

Answer: 8,611 meters

K2 rises 8,611 meters above sea level. That makes it the second highest mountain on Earth. Climbers call it the savage mountain because of its steep walls. It is far harder to climb than the taller Everest.

Answer: 10,984 meters

The Mariana Trench reaches 10,984 meters at its deepest point. Mount Everest would disappear completely under water there. There would still be over two kilometers of space above it. Only three people have ever been to the bottom.

Answer: About 147 trillion liters

The Dead Sea between Israel and Jordan holds about 147 trillion liters of water. Its water is almost ten times saltier than the ocean. That is why you can float in it with no effort. Even so, the sea shrinks by more than a meter every year.

Answer: 14,060,000 square kilometers

The Arctic Ocean covers 14,060,000 square kilometers in total. It is the smallest of the five oceans on Earth. A large part stays covered with thick ice all year round. Polar bears, seals and whales call it home.

Answer: 78,200 trillion liters

The Caspian Sea holds about 78,200 trillion liters of water. It is the largest lake on Earth by far. It is officially called a sea because the water is salty. Five countries sit on its shores, including Russia and Iran.

Answer: 377,000 square kilometers

The Baltic Sea covers 377,000 square kilometers in size. Nine countries sit along its coast, including Germany. It is the largest brackish sea in the entire world. Its water is far less salty than other seas around it.

Answer: 168,723,000 square kilometers

The Pacific Ocean covers 168,723,000 square kilometers. It is the largest ocean in the world by far. Every continent would easily fit inside it together. It covers almost one third of Earth's entire surface area.

Answer: ~2,500 kilometers

The Antarctic ice sheet spans about 2,500 kilometers across. It covers almost the entire continent. In some places the ice is up to four kilometers thick. If it melted, sea levels would rise by 60 meters.

Answer: 2,500,000 square kilometers

The Mediterranean Sea covers about 2,500,000 square kilometers. It borders Europe, Africa and Asia. 22 countries lie along its coast. Without the Strait of Gibraltar it would dry up in a few thousand years.

Answer: 436,402 square kilometers

The Black Sea covers 436,402 square kilometers between continents. It lies between Europe and Asia. Below 200 meters there is no oxygen at all. That is why many ancient shipwrecks rest there in perfect shape on the bottom.

Answer: 14,000,000 square kilometers

Antarctica covers about 14,000,000 square kilometers of land. That is nearly twice the size of Australia. 98 percent of it is buried under thick ice. Despite the cold it officially counts as the world's largest desert.

Answer: 3,357 meters

Mount Etna in Sicily stands 3,357 meters tall. It is the largest active volcano in all of Europe. Almost every year it spits out lava or ash. Still, over a million people live right at its foot in nearby villages.

Answer: 70,560,000 square kilometers

The Indian Ocean covers about 70.56 million square kilometers. It is the third largest ocean on Earth. Its area is almost 200 times the size of Germany. More than two billion people live along its coasts.

Answer: 138,600 square kilometers

The Adriatic Sea covers about 138,600 square kilometers. It lies between Italy and the Balkan coast. The Adriatic is fairly shallow, with an average depth of only 250 meters. It is part of the Mediterranean and a popular holiday spot.

Answer: 4,000 meters

The Pacific Ocean has an average depth of about 4,000 meters. That is more than ten Eiffel Towers stacked on top of each other. The Pacific covers one third of Earth's surface. It is bigger than all the land areas combined.

Answer: 1,205,000 square kilometers

The Greenland Sea covers about 1.2 million square kilometers. Germany would fit into it more than three times. Large parts are completely covered in ice during winter. It is a key home for polar bears and whales.

Answer: 570,000 square kilometers

The North Sea covers about 570,000 square kilometers. That is roughly one and a half times Germany's area. Its deepest point is only 700 meters down. Along the German coast tides rise and fall twice each day.

Answer: 5,450 meters

The Arctic Ocean reaches 5,450 meters at its deepest point. Down there it is pitch dark and freezing cold. Still, fish, crabs and squid live in those depths. The surface stays partly covered in ice all year.

Answer: 304 meters

The Dead Sea is about 304 meters deep at its lowest spot. Its surface lies 430 meters below sea level. That makes it the deepest lake on Earth. No fish can survive in its salty water, only tiny bacteria can live there.

Answer: 25,148 kilometers

Norway's coastline runs for 25,148 kilometers in total. That is as long as half of Earth's equator. The reason is the many fjords and tiny islands. Straightened out, it would wrap all the way around Africa twice.

Answer: 459 meters

The Baltic Sea reaches 459 meters at its deepest point. That spot is called the Landsort Deep near Sweden. Most other areas are much shallower, often just 50 meters. That is why it often freezes over in winter.

Answer: 300

An adult great white shark carries up to 300 teeth in its mouth. They sit in several rows, one behind the other. If it loses a tooth, a new one grows in right away. Over its lifetime, it uses up thousands of teeth.

Answer: 2,000

A whale shark swallows up to 2,000 small fish each day. To feed, it opens its giant mouth and just keeps swimming forward. Water is pushed out through its gills and the prey gets caught. Even though it is huge, the whale shark is harmless to people.

Answer: 90

There are around 90 whale species in the world. This group also includes dolphins and porpoises. The largest is the blue whale at over 30 meters long. The smallest is the vaquita porpoise, only 1.5 meters long. Some species live alone, others in big groups.

Answer: 100

A leatherback sea turtle lays about 100 eggs at once. She digs a deep hole in the sandy beach for them. Only a few hatchlings ever reach the sea. The mother returns her whole life to the same beach where she hatched herself.

Answer: Whale

The closest living relative of the hippo is the whale. Both descend from a common ancestor 55 million years ago. Scientists discovered this through DNA comparisons. Hippos and whales even share the ability to communicate underwater.

Answer: About 91

About 91 percent of marine animals are still undiscovered. Scientists know only around 240,000 species in the ocean. Every year about 2,000 new ones are added. The deep sea is less explored than the surface of the moon.

Answer: Up to 16,000

A humpback whale travels up to 16,000 kilometers per year. It moves between cold feeding grounds and warm breeding areas. During the trip it barely eats for months. The fat reserves still carry it through the long journey.

Answer: Up to 3,600

A blue whale eats up to 3,600 kilograms of plankton per day. Most of it is tiny shrimp called krill. One gulp takes in 80,000 liters of water that gets filtered out. In the feeding season, the whale almost doubles its weight.

Answer: Dolphin

Dolphins sleep with only one half of their brain at a time. The other half stays awake and keeps one eye open. This way they keep breathing and watch for danger. Many seabirds use the same trick while flying.

Answer: Bottlenose dolphin

After humans, the bottlenose dolphin has the largest brain to body ratio. Dolphins solve tasks, recognize themselves in mirrors and use tools. They even give each other names through unique whistles. That makes them one of the smartest animals ever.

Answer: Turritopsis jellyfish

The Turritopsis jellyfish can turn back into a young body. When it gets old or hurt, it restarts its life cycle. In theory it can live forever. Scientists call it the immortal jellyfish. This only works as long as the jellyfish does not get eaten.

Answer: Around 15 million dollars

One episode of the final Game of Thrones season cost around 15 million dollars. That is more than some feature films. Season eight cost 90 million dollars for six episodes total. The Battle of Winterfell alone took 55 nights to shoot. Over 750 people worked on that one episode.

Answer: 5

Money Heist has five seasons. The Spanish show is originally called La Casa de Papel. It first aired on Spanish TV and flopped there. Then Netflix bought it and made it a global hit. The song Bella Ciao became world famous because of the show.

Answer: 9

Seinfeld ran for nine seasons from 1989 to 1998. The show was called a show about nothing. Jerry Seinfeld turned down a tenth season. NBC offered him 5 million dollars per episode. He preferred to stop rather than see the show get worse.

Answer: Over 82 million households

Bridgerton season two reached over 82 million households in 28 days. That puts it among the most watched Netflix shows ever. The series is filmed entirely in England. Bath and Windsor Castle are well known locations. Fans travel to the UK just to visit them.

Answer: 14

Antarctica covers about 14 million square kilometers, larger than all of Europe. Under the ice lies a real continent with mountains and even lakes. No one lives there permanently, only scientists for a few months. A huge, white secret place on Earth.

Answer: Caspian Sea

The Caspian Sea is really the world's largest lake, not a real sea. It has no link to the ocean and its water is salty, but less so than the sea. Five countries surround it. A clever naming trick of geography.

Answer: 10,984

The Mariana Trench reaches about 10,984 meters down. If you dropped Mount Everest into it, more than two kilometers of water would still cover the peak. Only a handful of people have ever been down there. It is the darkest spot on our planet.

Answer: Ivory Coast

The Ivory Coast supplies about 40 percent of the world's cocoa. Many chocolate bars in Europe contain beans from there. The trees mostly grow on small family farms in the rainforest. Without these farmers there would be far less chocolate.

Answer: About 4,800 meters

The ice in Antarctica is about 4,800 meters thick at its thickest point. That is taller than many mountains in the Alps. Under the ice, a whole mountain range with lakes and valleys is hidden. If the ice melted, the sea level would rise by about 58 meters.

Answer: About 50 to 70 percent

Many people think that our oxygen comes mainly from forests. In reality, 50 to 70 percent comes from the sea. Tiny algae in the water called phytoplankton produce oxygen using sunlight. Without the oceans, we could not breathe nearly as well.

Answer: The Don Juan Pond in Antarctica

Many people think first of the Dead Sea, but that is not the saltiest place. Don Juan Pond in Antarctica is even saltier. Its water does not freeze even at minus 50 degrees Celsius because so much salt is dissolved in it. People could swim in it even with ice all around.

Answer: Antarctica

Many people think Africa with the Sahara is the driest continent. But in reality it is Antarctica. Almost no precipitation falls there because the cold air can barely hold any moisture. The ice has been lying there for thousands of years because it melts so rarely.

Answer: The Mid-Atlantic Ridge under the sea

Many people think right away of the Andes or the Himalayas. In reality, the longest mountain range is under water. The Mid-Atlantic Ridge stretches more than 65,000 kilometers through all the oceans. It is so long that it reaches halfway around the Earth.

Answer: The Atlantic Ocean

Many people think all oceans are the same age. But the Atlantic is the youngest. It formed when the continents of South America and Africa drifted apart about 180 million years ago. To this day, the Atlantic gets a few centimeters wider every year.

Answer: On Jupiter's moon Europa

Under the thick ice of Jupiter's moon Europa there is likely a huge ocean. It probably holds more water than all of Earth's seas together. Scientists hope to maybe find simple life there one day. A space probe is already on its way.

Answer: Over 200

The bowhead whale can live over 200 years. That makes it the oldest mammal in the world. Some animals still carry harpoon tips from the 19th century in their blubber. In the cold seas they swim very slowly and save energy.

Answer: About 50 percent

About half of the oxygen on Earth comes from tiny algae in the sea. They are called phytoplankton and are often smaller than a dust grain. Trees and plants on land make the other part. Without these tiny algae we could not breathe properly.

Answer: About 11 million

About 11 million tons of plastic trash end up in the oceans every year. That is the same as one full garbage truck entering the water every minute. Fish and birds often mistake small pieces for food. That is why avoiding plastic and sorting trash well matters so much.

Answer: 5364

The Mount Everest Marathon starts at 5364 meters at Everest Base Camp. That is higher than any peak in the Alps. The air up there holds only half the oxygen at sea level. Even top runners take nearly twice as long as usual.

Answer: around 2 million

The market is only open for about four weeks. The city of Nuremberg reported this figure for the 2024 season.

Answer: around 146 million

The year before, the figure was still 164 million. The German Confectionery Industry Association (BDSI) surveys its members on this every year.

Answer: around 18 million plants

The count covers production from July 2024 to June 2025. The figure comes from the German Federal Statistical Office.

Answer: around 126 billion euros

The German Retail Federation (HDE) forecast 126.2 billion euros for November and December 2025, with 22.2 billion of that coming from online shopping.

Answer: up to 91 kilograms

A blue whale mother's milk is extremely rich. That is why the baby gains up to 91 kilos every single day. That is more than a grown-up weighs (WWF, 2025).

Answer: About 7 kilometres

Under the oceans the Earth's crust is only about 7 kilometres thick. Under the continents it is often 30 to 40 kilometres. Compared to the whole Earth, the crust is as thin as the skin of an apple. Below it the hot interior of the Earth begins.

Answer: 0

Not a single person lives in Antarctica permanently. There are only research stations where scientists stay for a few months. In summer there are a few thousand people, in winter only about 1,000. Antarctica belongs to no country and is protected by a treaty.