Shoreline lakes are generally lakes created by blockage of estuaries or by the uneven accretion of beach ridges by longshore. They include maritime coastal lakes, ordinarily in drowned estuaries; lakes enclosed by two tombolos or spits connecting an island to the mainland; lakes cut off from larger lakes by a bar. A gut is a narrow coastal body of water, a channel or strait, usually one that is subject to strong tidal currents flowing back and forth. A gut may also be a small creek. Reeds morass wetland rush bed reed bed. A lagoon is a shallow body of water separated from a larger body of water by barrier islands or reefs. Lagoons are commonly divided into coastal lagoons and atoll lagoons. Gulf inlet sand dune inner sea.