Player's Handbook[]
The character has learned the arts of navigating by the stars, studying currents, and watching for telltale signs of land, reefs, and hidden danger. This is not particularly useful on land. At sea, a successful proficiency check by the navigator reduces the chance of getting lost by 20 percent.
Player's Option: Skills & Powers[]
Navigation: Characters with the navigation proficiency know how to fix their locations on the seas and oceans of the campaign world by observing celestial clues. Characters with a sextant (not necessarily available in all campaigns) and a compass, and who can see the stars or observe a sunrise or sunset, will know where they are—no proficiency check is necessary. Such a skilled character can navigate across entire oceans without becoming lost, though bad weather can obscure the celestial clues and blow a vessel far off course.
If a character does not have the proper tools, or is forced to work with only a general idea of direction (fog obscures the sunset, for example), the DM should secretly make the proficiency check. Success means the character is reasonably accurate in plotting the day's course. Failure means an off-course error that varies by the extent of the failure—a roll of 20 has the character going practically the exact opposite direction!
The Complete Thief's Handbook[]
Required: Buccaneer.
Recommended: Smuggler.
This proficiency is normally restricted to priests, warriors, and wizards. Its description is on p. 61 of the Player's Handbook.
Campaign Option: Council of Wyrms Setting[]
Navigation is described in the Player's Handbook. The proficiency allows a dragon to find its way by the stars, currents, and other signs. A successful check reduces the chance of getting lost at sea by 20%. Dragons also use this proficiency when flying long distances (out of their local territory).
Hatchlings can take this proficiency.