The boat will be attacked by waves of monsters. Kill them as fast as you can as the waves are timed. The first three waves consist of level 27 goblins. The next three waves consit of level 28 fairies. And the final wave consists of Lord Zaavan linked with two level 29 skeleton adds.
Killing Zaavan will close the quest. Zaavan also drops a treasure chest, which can be exquisite.
Talk to Captain Corrigan on the wheel deck. Chose the option "return to shore" while speaking with him to exit the instance.
The instance can be re-entered even after the quest is complete from a guild hall Mariner's Bell.
After the quest is complete, go to The Thundering Steppes and speak to Scholar Milnik on the docks, at ( -550, -16, -430 ) /waypoint -550, -16.45, -430. Select speak option "I traveled across the sea of mist" to choose your weapon reward.