* 90% of all volcanic activity occurs in the oceans.
* The speed of sound in water is 1,435 m/sec - nearly five times faster than the speed of sound in air.
* The record for the deepest free dive is held by Jacques Mayol. He dove to an astounding depth of 86m without any breathing equipment.
* Many fish can change sex during the course of their lives. Others, especially rare deep-sea fish, have both male and female sex organs.
* A mouthful of seawater may contain millions of bacterial cells, hundreds of thousands of phytoplankton and tens of thousands of zooplankton.
