A coastal inlet is a body of water that connects to the ocean and is often found along coastlines. The term 'coastal inlet' can be broken down into three parts: RIA (3 letters), FJORD (5 letters), and FIRTH (5 letters). A RIA is a river or stream that has been flooded by the sea, creating a long, narrow inlet. A FJORD is a deep, narrow inlet of the sea between steep cliffs, created by glacial erosion. Finally, a FIRTH is a large estuary, typically formed at the mouth of a river. All three terms are used to describe a coastal inlet.