71% of the Earth’s surface is made up of seas and oceans.

But we don’t know much about the ocean depths, because humans have only been able to get there recently, using special submarines.

The abyss or ocean bottom is about 3000 m deep and sometimes even 10,000 m!

To live in this extreme environment, animals have had to adapt and find survival strategies.

They’ve had to get used to a world without light, high pressure, icy temperatures and not much food.