SRD:Trident of Warning

Trident of Warning: A weapon of this type enables its wielder to determine the location, depth, kind, and number of aquatic predators within 680 feet. A trident of warning must be grasped and pointed in order for the character using it to gain such information, and it requires 1 round to scan a hemisphere with a radius of 680 feet. The weapon is otherwise a +2 trident.

Moderate divination; CL 7th; Craft Magical Arms and Armor, locate creature; Price 10,115 gp; Cost 5,057 gp and 5 sp + 405 XP.