Other forms: waterways
Any place you can navigate by boat is a waterway, whether it's a river, a stream, or a canal. The city of Venice, Italy is famous for having waterways instead of paved streets — to get around there, you'll need to hire a gondola instead of a taxi.
Routes that boats routinely travel are waterways, and they're most likely to be referred to that way when those boats are transporting goods. Maritime waterways are made up of straits and canals connecting two large bodies of water (such as oceans), and inland waterways include long rivers like the Colorado and the Nile. The 3,000 mile-long Intracoastal Waterway is made up of bays, inlets, and sounds, hugging the Atlantic coast of the U.S. down to the Gulf of Mexico.