Mankind has yet to understand well the ecosystem and the marine life in the depths of the oceans, lakes and rivers around the world.

Crystal-clear or murky. Relatively shallow or deep. Fresh or salt. There are so many things to discover about our water-dominated world.

Authorities don’t know why thousands of jellyfish packed a three-mile long section of San Francisco’s Ocean Beach recently – and are floating various reasons why there seems to be a proliferation of all types of jellyfish in the world’s oceans – an obvious issue that open water swimmers are aware of.

Photo above is of a piranha.

Copyright © 2011 by Open Water Source