Snorkeling spots (5)
I believe the answer is:
reefs
'snorkeling spots' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for reefs that I've seen before include "Submerged ridges of rock or coral near the surface of water" , "coral banks" , "Ridges of rock or sand beneath sea surface" , "Groups of submerged rock" .)