Enter the Maelstrom to appear in the Seacrest Grounds. Enter the Magic Forcefield south of Mr Brandon and swim to the north side of the water. Your mission is to find Brandon's Wedding Ring in the Seacrest Grounds. Talk to Mr Brandon and ask to assist him and accept the mission with yes.
You will encounter Devourers, Blood Beasts, Rot Elementals and Glooth Blobs. To get there you must leave Rathleton to the west. Go to Mr Brandon north-west of Rathleton to start this quest.