Just 30 years ago, dense, swirling schools of hammerheads and giant manta rays made the Sea of Cortés - El Golfo de California - a global diving mecca, and created the city of La Paz’ flourishing tourism economy. But in the 1990s, indiscriminate issuance of shark fishing permits allowed multinational fleets to “strip mine” them in critical habitats, including nurseries. This triggered a cascade of collapse among shark populations, so local fisheries and tourism plummeted. But today, scientists and fishermen work closely together to restore and protect this priceless marine ecosystem.