Low water mark: the highest reach of the water at low tide.

UNESCO: L O S S A R Y

Offshore zone: extends from the low water mark to a water depth of about 15 m (49 ft) and is permanently covered with water.

UNESCO: L O S S A R Y

But ahead of the London Games last summer, the U.S. failed to qualify as a team in the sport for the first time a low-water mark for a nation that dominated synchronized swimming from its glittery Olympic launch in 1984.

WSJ: Synchro de Mayo: A Struggling U.S. Sport Throws Itself a Party