A long, narrow , deep inlet of the sea between hills or mountains
A inlet of the sea or the wide mouth of a river is called a "Bay".
That would be a "fjord," which is a long, narrow sea inlet with steep sides or cliffs, typically formed by glacial erosion. In southern Ireland, these fjords are often a result of Ice Age glaciers shaping the landscape.
A fjord.
firth
A long, narrow, deep inlet of the sea between steep slopes
A long, narrow, deep inlet of the sea between steep slopes is a fiord.Sentence = "I saw a Fiord when I went to the sea side"....
Ria is a long narrow inlet.
A fjord is the long, narrow sea inlet formed by the submergence of a glacially-carved valley. Fjords typically have steep cliffs along their sides and are found in regions where glaciers have sculpted the landscape.
river
No, it is a sea inlet with a narrow mouth. This is called a 'gulf' .
Arm (of the sea) or bay can be used to describe a narrow inlet, although a bay can be up to 24 nautical miles wide.