Dol Aerrochben (S. "Hill of the Sea-knight") was an islet off the northern tip of Tolfalas. This islet possessed a fortification that housed the Master of the Straits, the royal officer responsible for guiding ships through the nearby narrows. The masters three rugged ships rescued shipwrecked seamen and braved vicious storms in order to deliver urgent messages to the mainland. A beacon stood adjacent to Dol Aerrochben, a few miles from the northeasternmost point of the main island. Even amidst the roar of the sea, the lights and bell-tolls from this beacon easily reached the great twin tower that commanded the summit of Dol Aerrochben.