rare n huge aquatic beast water 

Perception +21; darkvision

Languages Aquan (Can't Speak Any Language)

Skills Athletics +22, Stealth +23

Str +8 Dex +5 Con +5 Int -3 Wis +5 Cha +0

Slow Metabolism A water orm can go for 10 years without feeding. Beyond this limit, the water orm's hunger causes it to become slowed 1, but doesn't otherwise impact its lifespan. A water orm that's slowed as a result of starvation can remove this condition by using Swallow Whole to gulp down a meal.

Undetectable (abjuration, primal) A water orm automatically tries to counteract any detection, revelation, or scrying divination attempted against it, using its Stealth modifier for the counteract check.

AC  30; Fort +21, Ref +19, Will +17

HP 170

Speed 20 feet, swim 50 feet

Melee [>] jaws +24 (reach 15 feet), Damage 2d10+11 piercing plus Grab

Melee [>] tail +24 (agile, reach 15 feet), Damage 2d6+11 bludgeoning

Swallow Whole [>] (attack) Large, 2d8+8 bludgeoning, Rupture 22.

Water Travel [>>>] (primal, transmutation, water) A water orm can dissolve into water, appearing only as a long, dark, serpentine stretch of water. While in this form, a water orm's swim Speed increases to 600 feet, it automatically succeeds at Athletics checks to swim, and it gains a +4 circumstance bonus to Stealth checks in water. A water orm can remain in this form for 8 hours, but it can't enter salt water when using this ability. A water orm can return to its normal form using a single action which has the concentrate trait.

Bestiary 2, page 289.