An inlet is an indentation of a shoreline, usually long and narrow, such as a small bay or arm, that often leads to an enclosed body of salt water, such as a sound, bay, lagoon, or marsh. In sea coasts, an inlet usually refers to the actual connection between a bay and the ocean and is often called an "entrance" or a recession in the shore of a sea, lake, or river. A certain kind of inlet created by glaciation is a fjord, typically but not always in mountainous coastlines and also in montane lakes.