Yes, I think the terrain will be a big bonus. My only concern with it is that I could easily snap off a move by taking a 5min break at work on a blank map, and now that may not be as possible. But I'll go for quality over quanitity.
OOC: We didn't end up changing the rules on holding breath did we.
Okay, of all of the rules I've seen published for the effects of being underwater, which one are we using?
OOC: Hmm.. Since Charraw is Gargantuan, I think his head is above water. Then again his summoning would end long before his breath would give out. Since Homey is Huge, does he get the benefit of having 5ft of water over him?
Anyway...
Charraw will attempt to move the grapple right back up where it was before, since he's taller than the trench is deep. (However, I expect he should get a penalty for moving the grapple "uphill").
St. George's action will have to wait to see whether Charraw is successful or not.