From publisher blurb:
No time to whip up some aquatic-themed battle maps?
No problem! Here's your solution!
Includes 80 full concept battle maps--including a giant fish tank, a sunken ship, a beach-side village, sea caves, islands (including separate island tiles so you can customize your maps!), a swamp, a river, island ruins, island temples and a mermaid-theme dungeon!
All come with grid versions.
But that's not all! As a bonus, also included are 2 water overlays for tokens, medium and large sizes, so that your tokens can appear as if underwater!
Just add monsters!