Water Dragons

The water drakes originated in the Ladon Sea, before being scattered by the Cataclysm. They were never as populous as the drakes and wyverns, but have suffered less from the attentions of hunters.
Whereas land drakes are wingless, sea drakes are cliff-dwelling, winged water Dragons. They survive in large numbers on the north coast of Suto and the cliffs of central and southern Cairo. They are fish-eating divers, and make good steeds for those who value speed over dry-skin.
Swimming in deeper waters, sea serpents are wingless apex predators, hunting sharks and whales. Intelligent and pragmatic, younger sea serpents often have understandings, even alliances, with the Seafolk. Whether these alliances persist as the serpent grows older and larger depends on how much the serpent feels they are getting out of the deal.
Larger even than the sea serpents, the dragon turtles are true leviathans. Show and ponderous, but almost unassailable and powerful beyond comparison, they can grow large enough to be mistaken for islands in the open ocean. The Seafolk may bargains with young dragon turtles, but they regard the ancient specimens with nothing short of reverence. Full-grown dragon turtles are the ocean's might made flesh, and the most ancient of them enjoy almost godlike status.
Dragon turtles do not possess a connection to Dzenmisa, but do develop an elemental bond with the ocean, which can grow to a level which justifies their near-divine reputation. Unfortunately, not all of the waters of Aiaos are wholesome, and this affinity can render these living deities susceptible to Void-taint.
In inland waters, hydras lurk; massive and predatory, their multiple heads, being similar to those of Malards, can attract the worship of chromatic Dragonborn, especially in the case of draco-hydrae, winged hydrae capable of absording elemental energy to fuel their deadly 'prismatic' breath weapon.