I've been thinking about how there might be a connection in that Sabien decided to sabotage the ship so close to the Diver's Grave. Could the underwater temple-thing be associated with Uk'otoa?

It might just be a total coincidence/convenience for Matt as a DM to have the two locations near each other, but until it became clear that the blood ritual was used for summoning storms and not anything with the eye, I was almost positive that Sabien was trying to sacrifice Fjord's ship somehow. But there's nothing so far to suggest that Sabien has anything to do with Uk'otoa, right?