Coastal inlet
The Oxford English Dictionary describes inlets as, "a narrow opening by which the water penetrates into the land; a small arm of the sea, an indentation in the sea-coast or the bank of a lake or river; a creek." Inlets can refer to many different types of coastal and lake water formations, or even to a narrow body of water between islands.
Fjord, Canal, Calanque or Channel
Mouth of the Geiranger Fjord
During the Ice Age, massive glaciers dug deep into mountainous coastlines. They carved out deep, narrow inlets from the shore down into the ocean as they moved and changed. The glaciers slowly receded, leaving the mouth of these inlets, or fjords, trapped by ice longer than the areas close to the comparably warmer ocean. Thus, fjords are deeper at the mouth than they are at the opening to the ocean. A fjord is also known as a canal or channel in some regions. In the Mediterranean, they are known as calanques.
Bay, Gulf or Cove
Coves are formed when the sea passes a barrier and erodes a larger area inland.
Bays and coves are inlets formed by water erosion. In some cases, an inland river breaks through a barrier of relatively strong strata of earth to reach the sea. This allows the tides of the sea to reach the less resistant strata behind this wall. Thus, the opening remains small, while the body of water grows wide further inland. Coves can also be formed by the sea breaking through the resistant strata on its own, either by gradual erosion or by rising sea levels. Large bays are referred to as gulfs.
Sound
A dock in the Puget Sound, stretching out into one of the fjords
A collection of interconnected inlets in one area is called a sound. Two well known sounds in the U.S. are the Puget Sound and Howe Sound. These two sounds are primarily a system of fjord valleys filled by the ocean to become inlets. A sound may also refer to an inlet larger than a bay but smaller than a gulf. In northern Europe, a sound is called a sund, and refers to inlets called straights between land masses.
Mechanics
An inlet may refer to the part of a device that allows a substance, especially a fluid, from one section to another. For example, sinks have inlet conduits through which water may pass. The inlet valve would control the amount of fluid that passes. Machines designed to mix chemicals or solvents have inlets to allow the passage of fluids from one chamber to another. Switchboards operate with a system of electrical inlets, controlled by inlet switches.
Other definitions
According to the Merriam-Webster Dictionary, an inlet is also a generic term for "a way of entering; especially : an opening for intake." An inlet can be the entrance or opening of something, or the thing which enters. As a verb, inletting is allowing someone or something to enter, or refers to the act of inserting or inlaying.
Tags: body water, Puget Sound, resistant strata, which water
