Gulf of Maine
Like much of the continental shelf off the east coast of North America, the Gulf of Maine was above sea level during the last ice age. Georges Bank stands 330 ft (100 m) above the floor of the Gulf, and was an island until 6,000 years ago. Cape Cod and the islands of Nantucket and Martha’s Vineyard are the highest standing of a series of moraines left behind as the glaciers retreated and the sea level rose.
Occasionally, the Gulf Stream lies not far offshore and the temperature of the sea off Nantucket beaches can be several degrees higher than it is off nearby Cape Cod.
North of the Gulf of Maine, the Bay of Fundy extends more than 120 miles (200 km) inland. The bay acts like a funnel, producing a tidal range of 43 ft (13 m) at its northern end, which is the highest in the world.