From PathfinderWiki

The Rifardona is a massive sandbar over twelve miles long which shelters the port and city of Westcrown from the worst of oceanic tides. Ships sailing into the River Adivian through Gemcrown Bay must skirt the Gemcrown Cliffs at the sandbar's edges. The so-called "Reef of Aroden" can be treacherous to unwary ship-captains as evidenced by the large number of shipwrecks to be found here.1