So I have ideas for an underwater expansion for the old MB/GW game HeroQuest. I like a lot of the tiles from the Atlantis set so I picked it up, but I'm specifically looking for something to represent the ocean floor. Some of the beach tiles are ok, but pretty clearly above water. Anyone have any ideas on ways to adjust the tiles so they look submerged? I adding a tint with an image editor and it's ok, but mostly looks like my printer ran out of a certain color ink. There are some underwater tiles over at Roll20 that are for purchase, but I like the WWG stuff better and not sure which would be more work (trying to convert beach tiles to underwater or converting the Roll20 tiles to match the WWG standard). Any thoughts?

I would say it's definitely easy to convert beach tiles to underwater. I thought someone here did that as a kitbash, but I do not see it.

Have you tried overlaying a water tile over a beach tile and playing with the opacity and blend modes?

Seems like Lord Zsesz has some tiles like this. Some coral walls and props and kelp forests would look really cool though,