The Caspian Sea is also classed as the world's largest lake.
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 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.