Currently there are some creatures that clearly belong to the sea, such as sea crabs and cephalopods, that can be encountered in Lake Boethiah and the freshwater rivers in the Molagreahd Region, which is somewhat immersion breaking. I think the problem here is that these are included in the level lists and these regions also have large areas of sea water, so it might not be easy to fix, but it would be preferred if another solution could be found for these creatures. Maybe this would have to wait until the region assignments are changed some time in far future, though.