The Gulf Stream's warm and swift current runs swiftly from the Gulf of Mexico to the North Atlantic, where it splits at about 40°0′N 30°0′W to effect the North Sea and the ocean off Africa. According to Wikipedia the Gulf Stream is typically 100 kilometres (62 mi) wide and 800 metres (2,600 ft) to 1,200 metres (3,900 ft) deep. The current velocity is fastest near the surface, with the maximum speed typically about 2.5 metres per second (5.6 mph).
The sea off Fort Tilden, the Rockaways is swimmable thanks to the Gulf Stream.
As are the breakers off the Montauk Cliffs.
Atlantic rollers off the shore of Nantasket Beach.
But nothing could melt Newburyport slush in the winter of 2015.
Not even the Gulf Stream.
But I'm always ready for a swim off Palm Beach.