The Deep

Introduction > What is the deep?> Where is the deep?

The deep-sea is an undiscovered world. We have explored  the highest mountains and deepest valleys on land but only once have people ventured to the deepest portion of the ocean, the Marianas Trench (Pacific Ocean), when in 1960 the US Navy dived almost 11 km beneath the surface using the 'Trieste'.

Click here for a fly-through animation of the Marianas trench.

Who knows what other wonders are hidden in the deep-sea? Scientists have made a start but have investigated less than 4% of the deep-seabed. Only as recently as 1977 did scientists discover hydrothermal vents with their unique communities of marine life. Many of the large cold-water coral reefs featured on this site were only discovered in the last 10 or 15 years.

The deep-ocean is often thought of as a stable environment, characterised by cooler temperatures than the surface waters. Sunlight is quickly absorbed by seawater, with very little light penetrating beyond the first 200 m. Plants cannot grow without sunlight, so plant life is restricted to maximum depths of 50 m.