The roar that we hear when we place a seashell next to our ear is not the ocean, but rather the sound of blood surging through the veins in the ear.
There was once an undersea post office in the Bahamas.
If Antarctica's ice sheets melted, the worlds oceans would rise by 60 to 65 metres (200 - 210ft) - everywhere
The North Atlantic gets 2.5 centimetres (1in) wider every year.
The Caspian Sea is also classed as the world's largest lake.
Water is actually naturally blue.
Tidal forces between the Earth and Moon are slowing the Earth down and pushing the Moon further away.