Can you swim with the sharks?

The majority of our planet (about 70%) is ocean. Yet scientists still have a lot to learn about what lies beneath the ocean's surface. What we have discovered so far is fascinating.

How much do you know about the mysteries of the ocean?

Below are some fun facts to get you started. And please share additional factoids in the comments below.

• We've only explored less than 5 percent of the ocean. In fact, we have better maps of Mars and the moon than we do of the ocean floor. The first "Census of Marine Life" will be completed in 2010. It will feature a comprehensive list of all the life forms in the ocean.


• About 94 percent of life on earth is aquatic, according to Graham Hawkes, a world-renowned engineer and inventor.


• Mountains, valleys, volcanoes, canyons, lakes, waterfalls, and more can be found in the ocean. The longest mountain range in the world is found under water. The mid-ocean ridge spans 40,389 miles and is formed by the movement of the Earth's tectonic plates. The first divers explored the mid-ocean ride in 1973, four years after Neil Armstrong set foot on the moon.


• The Great Barrier Reef is large enough to be visible from space. In fact, it's the largest living structure on earth. Coral reefs are some of the most diverse ecosystems in the world and are sometimes referred to as "the rainforests of the sea."


• There are more artifacts and historical remnants in the oceans than in all the planet's museums combined.


• Whale sharks are the biggest fish in the sea. They can grow to up to 50 feet and weigh in at a ton.


• Many of the foods we eat contain ingredients from the ocean. Peanut butter, for example, is easier to spread because it contains carrageenan (compounds extracted from red algae).

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