Deepwater. I guess this is the view of the editors of this particular site. I don’t think there are hard and fast rules and other “experts” may have different views.
I am happier with this than with 11d where the [thematic word] treatment seems to have been applied to [clue answer] when it is usually associated with the longer word [clue answer]+man. The [thematic word] usually affects whole words rather than part words.
That said I think what is intended is pretty obvious and overall it is a very good puzzle.