After a few moments, Sister Isolde sort of...melted away. It seems it was some sort of vision to mask an attack. There is a giant, tentacled monster attacking us physically and psychically! It took a while to pull the captain out of her beglamourment, and the creature swam around a lot, making it very hard to engage. It eventually broke the boat that half the party was using for air, so they had to abandon the fight. Finally, I managed to engage it and keep it from zooming around (almost dropping my mace in the process), long enough for Cap to zap it to death. Thank The One!
With the creature dispatched, Mimi's Sextant led us to some sort of Gailatian hatch. Unfortunately, Aerathor had to surface, but the rest of us got inside. It seemed to be some sort of large vehicle, but with no obvious means of locomotion or control. Getting in half-flooded the compartment, but we were able to find and extract a small chest containing another letter and two apparently Gailatian objects. I feel as if the image we chase comes just a little more in view with every discovery, but there is still so much to uncover!