Underwater 24 / 7 at level one

[Particle_Man]

If I were to run an underwater campaign (always underwater) what pc races could be played from level one?

[PossibleCabbage]

Merfolk, Aquatic Elves, Caecelias, Tritons, Gillmen, and Locathahs come to mind. Have you had a chance to look at the recent Player Companion "Blood of the Sea"?

[Diachronos]

Undines (trade out their SLA for the aquatic subtype and amphibious ability)
Merfolk
Wyrwoods
Seascarred (wereshark-kin) skinwalkers
Aquatic elves
Gillmen

Some races get the ability to hold their breath for longer periods of time, but they'd still need to come up for air eventually.

EDIT: Forgot about tritons and locathahs. Cecaelias, sahuagins, grindylows, and adaros are also good races for underwater campaigns, but they're all extremely powerful races (20+ RP) and might not be good for PCs to choose.