uncommon cg huge amphibious dragon water 

Perception +21; darkvision, wavesense (imprecise) 60 feet

Languages Aquan, Auran, Common, Draconic, Elven

Skills Acrobatics +23, Arcana +18, Athletics +26, Deception +19, Intimidation +21, Nature +22, Society +18, Stealth +21, Survival +20

Str +6 Dex +5 Con +4 Int +2 Wis +4 Cha +3

AC  33; fed by metal; Fort +22, Ref +25, Will +20

HP 225; Immunities paralyzed, sleep

Frightful Presence (aura, emotion, fear, mental) 90 feet, DC 30 (page 305)

Vortex (aura, water) 40 feet. Water in the aura that's also in the same body of water as the dragon is difficult terrain for Swimming creatures which don't have the water trait.

Liquefy [R] (abjuration, arcane, water) Trigger The dragon is targeted by a Strike or spell that could deal fire or physical damage to them; Effect The dragon liquefies, turning entirely to water while maintaining their shape, for a split second. Against the triggering effect, they gain resistance 20 to fire and to all physical damage.

Speed 30 feet, fly 100 feet, swim 50 feet; water walk

Melee [>] jaws +26 (magical, reach 15 feet), Damage 3d10+12 piercing plus hyponatremia

Melee [>] claw +26 (agile, magical, reach 10 feet), Damage 3d8+12 slashing plus Grab

Melee [>] tail +26 (magical, reach 25 feet), Damage 3d8+12 bludgeoning plus Grab

Arcane Innate Spells DC 32; 2nd create water (at will), endure elements (self only); Constant (2nd) water walk

Rituals DC 32; control weather (doesn't require secondary casters)

Breath Weapon [>>] (arcane, evocation, water) The dragon shoots a ball of water that deals 13d6 bludgeoning damage in a 25-foot burst within 50 feet (DC 32 basic Reflex save). All non-magical fire in the radius is extinguished. The dragon can't use Breath Weapon again for 1d4 rounds.

Coiling Frenzy [>>] The dragon makes one claw Strike and one tail Strike in either order, each against the same target. If either Strike hits, the dragon automatically Grabs the target.

Draconic Momentum The dragon recharges their Breath Weapon whenever they score a critical hit with a Strike.

Greater Constrict [>] 3d8+6 bludgeoning, DC 30 (page 305)

Hyponatremia (water) A living creature that takes damage from the sea dragon's jaws Strike must succeed at a DC 32 Fortitude save or become sickened 1 as a surge of excess water floods its body.

Bestiary 3, page 78.