From analysis of the multiple arrivals of the pulses, it is possible to learn water conditions at many depths, and to map the ocean in three dimensions.
It was deep in the then-uncharted reaches of the Pacific Ocean in November 1820 that disaster befell the Essex, in the form of a 26-metre bull sperm whale that rammed the ship's bow, sinking it and leaving the 20 survivors to a 96-day voyage across open ocean in three small boats.
She insisted on landing just the way the Navy did -- a perilous 130-mile-an-hour dive and a violent stop on a four-and-a-half-acre steel deck in the middle of the ocean in two seconds.
An estimated 40 cubic miles (167 cubic metres) of rock fell into the ocean in one go, resulting in an 800ft (244m) high tsunami wave that engulfed an island more than 30 miles away (48km).
Proof, if any were needed, that changes in the ocean can have freak effects thousands of miles away.There was a time when meteorologists looked on the ocean in two contradictory ways: as an infinite reservoir of heat and water, and as a passive recipient of changes in the atmosphere, cooling or warming in response.
Black-and-white dragons swirl in the spiraling eddies of ocean in "Nine Dragons," a 10-meter-long scroll by Chen Rong from around 1244, while a bald, roly-poly scholar looks introspective in "Two Chan Patriarchs Harmonizing Their Minds," half a diptych probably painted by Shi Ke in the 13th century.
In the last six years, Enric's team has helped inspire leaders to protect a total of 2.2 million square kilometers of ocean in six countries.
One bird was found to have covered of ocean in eight months, traveling northwards to the northern Labrador Sea then southeastward to the mid Atlantic before returning to land.
In February, water regulators cited the city for letting tens of thousands of gallons of sewage reach the ocean in six spills since 2005.
It is connected by a narrow spit of land to an offshore peninsula, with bays facing the ocean in two directions.
We climbed about 1,500 feet to the ridgeline on a rutted dirt road lined with eucalyptus trees and prickly pear cactus, then spent a happy few hours taking in ocean views in three, sometimes four, directions.
