Mag Bay is about the size of San Francisco Bay, and the largest villages in the area are Puerto San Carlos—population: 5,500—and Lopez Mateos, which are a bit rustic to say the least. These are commercial fishing villages, where local knowledge is passed down from father to son. Close to 100 miles of mangrove-lined channels and shoreline encircle the area, and where the mangroves stop, the desert takes over. There is no dependable water source in the region, which has greatly restricted development; there are also no big-boat marinas, very few hotels and a minimal supply of reliable fuel. It’s one of Baja’s last frontiers, but there are few other places on Earth where so many billfish congregate so predictably.