Sea serpents have long been the stuff of maritime legends, but despite countless attempts to hunt them, they are rarely encountered unless they wish it. As a full-round action while in water, a sea serpent can move up to its run speed (300 ft.) without leaving any trace of its passing (identical in effect to a pass without trace). An elusive sea serpent gains a +40 circumstance bonus to its Stealth check. In addition, except when in combat, a sea serpent is considered to be under the effects of a nondetection spell. Both of these spell effects are at caster level 20th and cannot be dispelled.