As water is much denser than air, this pressure increases as we venture into the water. For every 10m we decend into the depths of the ocean one more atmosphere of pressure pushes down on us. For example, at 20m deep we have three atmospheres of pressure pushing on us - two from the water and one from the air pushing on the sea's surface.

To travel into this high-pressure environment we have to make some adjustments. Humans can stand three or four atmospheres and still be okay. To go farther down we need to decend in a submarine.

Animals that live in the watery environment of the oceans undergo large pressure changes in short amounts of time - something that would give us 'the bends'. Sperm whales make hour-long dives 2,250 meters down. This is a pressure change of more than 223 atmospheres! By studying and understanding how these animals are able to withstand great pressure changes, scientists will be able to build better tools for humans to make such journeys.

Tides