Your new Prospirit watch says that it is water resistant fifty meters If you were to go swimming for maybe two hours going no deeper than fifteen feet would this new ten dollar watch survive?

Yes......your watch will survive. Water resistance,specified at 50 meters, is based

on water pressure caused by depth, not time. Fifteen feet is only about 5 meters.

You could put the watch in the water for 2 days at only 15 feet and it should do just fine. You could Scuba dive at 30 feet for 5 hours and the watch will survive.