From PathfinderWiki

The great lighthouse of Hor-Aha is located in a small island north of the Coast of Graves in Osirion. During the height of Ancient Osirion, the lighthouse was a key navigation aid. Its magic light not only marked the location but also gave information about the upcoming weather. Hor-Aha has remained dark for thousands of years, but recently lurid red and purple light strobes from its lantern room, the sign of violent gales. The few vessels that made landfall on the small isle were never heard from again.1