The Oxford English Dictionary defines “fiord” as a long narrow inlet of sea between high cliffs. The only significant watercourse on the east coast of the United States is the Hudson River. It extends 315 miles from Lake Henderson in northern New York to the Atlantic Ocean via New York Bay. The river was formed during the last Ice Age (about 20,000 years ago). During that period, sea level was much lower and the river extended much further south and east than it does currently. That old portion, now a submarine canyon, is sometimes referred to as a drowned river. The current river is named for Henry Hudson, who explored the river up to Albany in 1609, sailing for the Dutch in the vessel Half Moon. Native Americans had referred to the river by many names, including the Great Mohegan and the river the flows two ways. This latter name refers to the fact that the Hudson is tidal as far upstream as present-day Albany. The first known European to navigate the Hudson was the Portuguese explorer Estevão Gomez. In 1525, sailing for Spain in the 50-ton caravel La Anunciada, he searched the North American coast (from present-day Nova Scotia to the mid-Atlantic states) unsuccessfully for the Northwest Passage. He examined lower reaches of the Hudson River, which he referred to as the San Antonio River. His explorations, including the San Antonio River, were included in the surprisingly accurate 1529 map of America by Diogo Ribeiro. Giovanni da Verrazano, sailing for France, had entered New York Harbor the year previously, but considered the river to be a mere estuary not worthy of examination. When the Dutch settled Manhattan, they referred to the river as the North River, with the South River being the Delaware, where they had established a colony at Lewes. After the English replaced the Dutch colony in and around Manhattan, they started referring to the river by its present name, but many still use the term North River. The Hudson is joined by the Mohawk (its major tributary) just north of Albany. Near Albany is also the eastern terminus of the Erie Canal.