Like some pools
I believe the answer is:
tidal
'like some pools' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for tidal that I've seen before include "Concerning the rise and fall of the sea" , "Of sea, rising and falling" , "going with the flow" , "Type of wave" , "(Of the sea) ebbing and flowing" .)