XP 600
N Large vermin
Init +1; Senses watersense 60 ft; Perception +0

AC 12, touch 10, flat-footed 11 (+1 Dex, +2 natural, -1 size)
hp 13 (3d8)
Fort +3, Ref +2, Will +1
Defensive Abilities jet, transparent; Immune vermin traits

Speed swim 10 ft.
Melee tentacles +3 (1d6 plus poison and grab)
Space 10 ft.; Reach 10 ft.

Str 11, Dex 12, Con 10, Int --, Wis 10, Cha 2
Base Atk +2; CMB +3 (+7 to grapple); CMD 14 (can't be tripped)
Feats Weapon Finesse^B
Skills Stealth +5, Swim +8; Racial Modifiers +8 Stealth

Jet (Ex)

A monstrous jellyfish can jet backward once per round as a full-round action at a speed equal to four times its swim speed. It must move in a straight line, but does not provoke attacks of opportunity while jetting.

Poison (Ex)

Tentacle--injury; save DC 13; frequency 1/ minute for 6 minutes; effect 1d6 Dexterity damage; cure 2 consecutive saves. The save DC is Constitution-based and includes a +2 bonus.

Transparent (Ex)

A monstrous jellyfish is nearly invisible floating in the water. An observer must succeed on a DC 20 Perception check to notice the jellyfish.

Watersense (Ex)

Monstrous jellyfish can automatically sense the location of anything within 60 feet that is in contact with water.