Shark Junction (2014)

Roca Partida looks little more than a rocky outcrop inhabited by seabirds. But below the waterline, the steep mountainous walls are surrounded by the greatest concentrations of fish of any reef in the world. This tiny island is one of four in the Revillagigedo archipelago, better known today as the Socorro Islands. Mexicans call it their 'very own little Galapagos'. Like the other great, internationally recognized marine sanctuaries, the islands have unique wildlife. They are the only place in the world to find the Clarion Angelfish. Squadrons of these bright orange cleaner fish are vital to the health of giant Pacific manta rays found in large numbers here. Huge schools of fish, especially jacks and tuna, provide a bountiful food source for large shark populations. Silky sharks, scalloped hammerheads, Galapagos sharks and silvertip sharks are seen in numbers rarely found in the world's oceans. Thanks to the clash of two great ocean currents, the tropical seas around Socorro feed a bustling underwater city of marine life. Whitetip reef sharks are among the most obvious residents of the steep reef walls. What makes Roca Partida so bizarre is how these sharks live their daily lives, piled on top of one another, sometimes three-deep, as they seek out any resting place they can. They are forced to share the rocks and ledges with giant lobsters and moray eels, making for an uneasy truce with critters that would normally be either prey or predator. Humpback whales visit the islands annually, to calf and to breed. They are seen caring for their young before the long journey back to the Arctic, revealing a gentle side of Socorro. At other times of the year, we witness action-packed baitball scenes with sailfish demonstrating their deadly killing techniques. Socorro's extreme shark behaviour is in full throttle when another baitball attracts hundreds of sharks and tuna attacking the fish until the bitter end. These islands may be small but they are more than a match for some of the biggest names in the world's shark hall of fame.