A trident of yearning looks exactly like any normal trident, and its dweomer is also indistinguishable from the magic aura of other enchanted weapons of this sort. 

Any character grasping this type of trident immediately conceives an overwhelming desire to immerse himself or herself in as great a depth of water as is possible. The unquenchable longing so generated causes the affected character to instantly proceed toward the largest/deepest body of water—in any event one that is sufficient to completely cover his or her person—and immerse himself or herself therein permanently. 

The character cannot loose his or her grip on the trident, and only a water breathing spell (after submersion) placed upon him or her, or use of a wish or alter reality, will enable the character to do so. 

The trident is otherwise a -2 cursed magical weapon. 

Note that this item does not confer the ability to breathe underwater.