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Yes, but it's 3pp. The review of Cerulean Seas says that it has all kinds of rules, goodies and monsters for this kind of thing.
IIRC there is a soon-to-be-released book from Paizo specifically about underwater adventures...
Oh, Here it is: Aquatic Adventures for sometime next June.
The CRB talks about water pressure:
Very deep water is not only generally pitch black, posing a navigational hazard, but worse, deals water pressure damage of 1d6 points per minute for every 100 feet the character is below the surface. A successful Fortitude save (DC 15, +1 for each previous check) means the diver takes no damage in that minute. Very cold water deals 1d6 points of nonlethal damage from hypothermia per minute of exposure.
The GMG talks about how to avoid pressure damage:
[...]Pressure damage can be avoided entirely with effects such as freedom of movement.
Polymorph spells are perhaps the most useful in water, though, if the form assumed is aquatic in nature.
Natural Adaptation: Any creature that has the aquatic subtype can breathe water easily and is unaffected by water temperature extremes that are found in that creature’s typical environment. Aquatic creatures and creatures with the hold breath ability are much more resistant to pressure damage; they do not suffer damage from pressure unless they are moved instantaneously from one depth to another in the blink of an eye (in which case they adapt to the pressure change after successfully making five successive Fortitude saves against the pressure effects).
So Freedom of Movement and appropriate polymorph spells will do the trick. I personally also allow the Life Bubble spell to protect against pressure hazards, as it provides a "1 inch shell of tolerable living conditions". Any of these options can be achieved by using scrolls that grant the appropriate spells.