Neptune's domain (3,3)

I think it could be either:

Which length description are you looking for?:

3,3

sea

'neptune's domain' is the definition.
(I've seen this in another clue)

This is the entire clue.

(Other definitions for sea that I've seen before include "The Med, e.g." , "& 14 Ozone" , "Watery expanse" , "host of 1d [ADVENTURE]" , "Large expanse of water" .)

I've seen this clue in the Universal, the King Feature Syndicate and The Star Tribune.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.