The Intracoastal Waterway (ICW) is a 3,000-mile (4,800 km) inland waterway along the Atlantic and Gulf of Mexico coasts of the United States, running from Massachusetts southward along the Atlantic Seaboard and around the southern tip of Florida, then following the Gulf Coast to Brownsville, Texas. Some sections of the waterway consist of natural inlets, saltwater rivers, bays, and sounds, while others are artificial canals. It provides a navigable route along its length without many of the hazards of travel on the open sea.

A body of water, such as a river, canal or lake, is navigable if it is deep, wide and calm enough for a water vessel to pass safely. Navigability is also referred to in the broader context of a body of water having sufficient under keel clearance for a vessel.