This is my 100% honest reaction to this request:

Adding water mounts wouldn't make it possible to swim between maps, even if they made you immune to slaughterfish.

The slaughterfish aren't the real problem, they're just an effect added to hide the real problem - which is hitting the edge of the map. If you've ever tried to go over the edge of a map on land, where you come to a cliff too steep to climb that goes all the way around the edge then it's the same idea, only more deadly.

So if you were able to swim/ride past the fish all that would happen is you'd hit an invisible wall (if they've put one in), hit the actual edge of the 3D space (probably a cube) the map is built inside and get a weird effect where your character appears to be walking/swimming without going anywhere and the images go all blurry or end up somewhere that looks like this:



Or all of the above. It depends on how the map is built.

The point is you couldn't swim to another map, except in the places where it's already possible because ESO is not an open-world game (where the entire world is built inside a single space) and is not programmed to have all the edges of all the maps join up with all the corresponding edges of all the other maps - that only happens at certain points, where we can already go between them.

As far as I know (I'm not an expert on this) there are 2 possible ways to change that - one is to match up all the edges of the maps so we can move between them at any point, and add additional maps for areas like Iliac Bay which are currently not in the game. But that would be an incredibly huge amount of work for a relatively minor benefit. Especially adding all the water areas where all we can do is swim along the surface.

The other would be to add ships, swimming mounts or other objects that follow a fixed path through those areas (or more likely plays a cut scene that shows you riding it). Which still wouldn't allow you to explore them, but would at least allow you to cross them.

I'd just like to stop getting unhorsed because I hit that one spot in the river that was six inches too deep for it.

OR, you could let us vampires have mist form thats real mist form. and not make us into a ball but actually make us turn into mist and fogg.

Can't we just get a swimming animation for existing mounts so we don't have to dismount every time we want to cross a river? I don't care if they swim at the same speed as the character would swim if they dismounted, btw.