Legendary Tracker( Complete Adventurer, p. 192)
You can track prey across or through the water, or even through the air.
You can track creatures across water, underwater, or through the air by the minute disturbances they make and traces of their passage. This benefit adds the surfaces of water, underwater, and air to the list of surfaces found under the Track feat in the Player's Handbook: Surface DC. Water -------- 60. Underwater - 80. Air ----------- 120.