A body of water or waterbody (often spelled water body) is any significant accumulation of water on the surface of Earth or another planet. The term most often refers to oceans, seas, and lakes, but it includes smaller pools of water such as ponds, wetlands, or more rarely, puddles. A body of water does not have to be still or contained; rivers, streams, canals, and other geographical features where water moves from one place to another are also considered bodies of water. Most are naturally occurring geographical features, but some are artificial. There are types that can be either. For example, most reservoirs are created by engineering dams, but some natural lakes are used as reservoirs. Similarly, most harbors are naturally occurring bays, but some harbors have been created through construction. Bodies of water that are navigable are known as waterways. Some bodies of water collect and move water, such as rivers and streams, and others primarily hold water, such as lakes and oceans. Bodies of water are affected by gravity, which is what creates the tidal effects on Earth. Moreso, the impact of climate change on water is likely to intensify as observed through the rising sea levels, water acidification and flooding. This means that climate change has pressure on water bodies. Types Bodies of water can be categorized into: Rain water Surface water Underground water Note that there are some geographical features involving water that are not bodies of water, for example, waterfalls, geysers and rapids. Arm of the sea – also sea arm, used to describe a sea loch. Arroyo – (southwest US) (seasonal) a usually-dry bed of a steep-sided stream, gully, or narrow channel that temporarily fills with water after heavy rain. See also wadi. Artificial lake or artificial pond – see reservoir (impoundment). Aubach Barachois – (Canada) a lagoon separated from the ocean by a sand bar. Basin Bay – an area of water bordered by land on three sides, similar to, but smaller than a gulf. Bayou – (southern US) a slow-moving stream or a marshy lake. Beck – (UK) a small stream (esp. with a rocky bottom); creek. Bight – a large and often only slightly receding bay, or a bend in any geographical feature. Billabong – an oxbow lake in Australia; a pond or still body of water created when a river changes course and some water becomes trapped. Boil – see