Just killed him today with a guild group. He likes to stun-spin you when you first get his attention.
Pull him to shore and get on a ride and the spinning part of the spell well stop. Then you just have to beat him down. He has a lot of HP.

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Fabled Dragon Hero Bracer
Fabled Shield of the Water Dragon
Orb of Tishan
Pod of Seawater
Sea Dragon Meat
Spell: Sha's Ferocity
Spell: Visions of Grandeur
Torn, Frost covered book
Treasure Hunter`s Satchel
Water Dragon Scales