I think it would be cool to treat the different waters throughout PTR similar to the regions on land - by that I mean that having one or two different unique flora types per major river or sea would be really cool. For example, the Smear Algae was made by Fluxbender specifically with the intention of cluttering the Thirr, and Eyestars would fit the purpose equally well. Similar small underwater additions could be included once TR reaches the Padomaic coast, perhaps to be shared with the Padomaic Isles project, as uniquely Padomaic Ocean underwater clutter. TES 3 is unique in its levels of exploration, underwater exploration being one of them, and using the same clutter everywhere both makes no sense from a worldbuilding sense, as well as taking away from the sense of excitement of exploring different waters from a gameplay perspective.