Ria is a long narrow inlet.
Fjord .
slough
Could be a Cove
The word is ria. It means a long, narrow inlet.
ria
Ria
sound
Ria
The word Mollusk is a 7 letter word.
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.
an inlet