Seaverns are powerful aquatic serpents that take inspiration from both real-life plesiosaurs and the mythological Leviathan. They are described as kings among sea serpents and are known for destroying any ship they come across. They have dark indigo bodies with blood red undersides, long horns, a tall crest on top of their heads, and a fin on their backs. Their crests and fins are gold-coloured, while the webs on their feet are dark blue. They are among the most powerful monsters of the sea, able to emit bloodcurdling roars from their maws that strike fear into the hearts of adventurers and then calling forth enormous tidal waves to finish them off. In Dragon Quest IX, it is said that seasaurs will transform into seaverns after consuming plum stones.
True masters of the sea, these supreme seasaurs scare foes silly with a blood-curdling cry, then smash them with a tsunami.
Dealers of watery death, they rise from the depths to bring terror and destruction to all the oceans of the world.
During Quest #173: Plum Duffer, the player must obtain ten plum stones from defeating seaverns in high-level water grottoes. The stones will always drop after defeating a seavern, but only when the quest has been accepted. The quest can be repeated as many times as desired.