Exploring Oceans

Oceans currently cover about 70% of Earth's surface and occupy over 95% of Earth's volume thought to be habitable.  Oceans average about 4 deg-C and 4km deep, with trenches down to almost 11km.  The ocean floor is nowhere more than 200M years old, compared to Earth's 4550M years, and subject to about 1100 times sea level pressure, yet active with volcanoes, lava flows, hot vents - and life.

New underwater robots are rapidly advancing our ability to explore Earth's oceans, though over 99% of Earth's oceans still remain to be newly explored.