Since there is a good amount of underwater combat, I would suggest picking up Pathfinder Campaign Setting: Aquatic Adventures for the rules expansions on running underwater combat. For player options, I'd suggest Pathfinder Player Companion: Blood of the Sea.
Removed posts. Leaving Adam's reply so the OP has access to the answer. "fanboy slobbering" is an inappropriate descriptor for reviews other community members have left. If someone wants to restart conversation about good supplements for a Ruins of Azlant campaign, you are welcome to do so in a new thread.
