Coastal features (6)
I believe the answer is:
inlets
'coastal features' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for inlets that I've seen before include "Silent as sea entries to land" , "Bays or coves" , "Silent kind of water channels" , "Small arms off larger bodies of water" , "Silent strips of water" .)