Are you ready to step up your scuba-diving game? As a new diver, you started in the pool, of course. Then you waded off the shore and slid off the back of boats. The best spots by land have vibrant reefs, schools of colorful fish, and graceful sea turtles en route to their nesting grounds. But, most of the time, they’re missing something. An element of danger. It’s time to go see the sharks.

The Revillagigedo Islands are a shark lover’s paradise. Grey reef, oceanic whitetip, silky, and even the occasional tiger shark patrol the deep waters surrounding the islands. Schools of Moorish idols and triggerfish—fish you’re used to seeing—are joined by trumpetfish and huge tuna. Humpback whales prefer the area’s warm water to Alaska’s bitter cold for breeding. While friendly bottlenose dolphins seem to guide you toward the right spots.

So where is this little Galápagos? Since it sounds like the islands are lost in the middle of the Pacific Ocean, you’re surprised to learn how close they are to Mexico. The four volcanic islands lie 240 miles southwest of Cabo San Lucas, the southern tip of the Baja California Peninsula, and 450 miles west of Manzanillo. With no fresh water, San Benedicto, Socorro, Roca Partida, and Clarión Islands have always been uninhabited, except for visiting scientists. Plus, since 1994, it’s been a biosphere reserve that protects not only the sea creatures in the water, but breeding and migrating seabirds on the steep land.

It’s because of these birds that people are no longer allowed on the islands. The lightweight Socorro elf owl is already extinct, while the Socorro dove, similar to a mourning dove, is no longer found in the wild. UNESCO wants to ensure that endangered Socorro mockingbirds and Socorro parakeets don’t meet the same fate. Visitors must overnight on boats, whether they’re part of a tour or on a private vessel. You’ll spend much of your time in the water anyway, though. Your first dive with hammerheads begins shortly after sunrise around San Benedicto Island.