It would be nice to have Sea Monsters as World Bosses one day as they are displayed on the ESO World Map. The Sea monsters on the world map of ESO you will see that they have five Sea Monsters. One is a big Octopus, Three Sea Serpent ( two small Sea Serpent & One big Sea Serpent) and a Sea Monster that look like the Crackin. So far the only four Sea Monsters I see are two Monsters size Mudcrabs the Titanclaw ( in Southwest Stormhaven ) & Shellcracker ( in Stonefalls ) and two Dreugh, Brood Queen ( in West of Wayrest ) & Dreugh Matrons ( in Stonefalls ).

If you have played Skyrim mods on Nexus you'll remember the mods called Here There Be Monsters. Where there's nine momsters in the quest you have to track down and defeat them. I will say its a pretty good add-on mod if your in to Giant Monsters or Sea Monsters.
Bluntly speaking Sea Monsters that I basically want to see added in to ESO are the Three-Headed Sea Serpent, the Giant Water Atronach and WereShark if not it's all good with me about the ones on the map to be including instead.