Ok, for the upcoming adventure it looks like we will be going underwater. And in core...apparently polymorph spells are the ONLY way to get a swim speed. So! Kiri is willing to Polymorph Any Object people if they'd like (regular poly only lasts for minutes).
DR has approved these forms which are legal PAO forms:
[sblock]Chuul
Giant Squid
Kapoacinth Gargoyle
Scarag Troll
Locathah
Aquatic Elf
Sahaugin
Dire Shark
Sea Hag
Merfolk[/sblock]
NOTE: Unlike normal Polymorph, PAO gives you the Intelligence of the form, on top of str/dex/con. Which means none of these are good choices for Val (I think he'd be best off using Alter Self for a humanoid form w/ swim speed). For Szitha, Szen, and Eionia, the best options are probably Troll or Gargoyle, if you wish to still fight with your weapons and be able to speak. You would gain Aquatic subtype, which includes swim speed and water breathing, and in the case of most of those forms, duration would be permanent (I can dispel it later). Szitha should still prep Water Breathing as a backup (and I guess Val would need it, possibly also me), and Eionia may want Freedom of Movement so her (not piercing) weapon doesn't suffer penalties (-2 to hit and damage halved) underwater.
[sblock]And for my own personal notes, the following forms are eligible for Shapechange and allowed:
Water Elemental
Kraken
Elder Tojanida[/sblock]