A floating market on one of Thailand's waterways
A waterway is any navigable body of water. Waterways can include rivers, lakes, seas, oceans, and canals. In order for a waterway to be navigable, it must meet several criteria:
- The waterway must be deep enough to allow the draft depth of the vessels using it;
- The waterway must be wide enough to allow passage for the beam width of the vessels using it;
- The waterway must be free of barriers to navigation such as waterfalls and rapids, or have a way around them (such as canal locks and boat lifts);
- The current of the waterway must be mild enough to allow vessels to make headway.
Vessels using waterways vary from small animal-drawn barges to immense ocean tankers and ocean liners, such as cruise ships.
Canals are artificial waterways that are constructed to provide a new path of travel for vessels (as opposed to improving a natural waterway along its current course). At one time, canals were built mostly for small wooden barges drawn by horses or other draft animals.Today, major canals are built to allow passage of large ocean-going vessels (see Ship canal) to connect harbours with or create a shortcut between seas and existing waterways, such as the Kiel Canal between the North Sea and the Baltic Sea, which is the most heavily used canal worldwide.