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Finding Bull Sharks in Islas Murcielagos

Often overshadowed by Cocos’ legendary reputation, the diving off Costa Rica’s west coast is spectacular in its own right, as I discovered when I traveled there two summers ago.

Most divers know that Cocos Island in Costa Rica is one of world’s best shark-diving spots. But that there are amazing shark-diving opportunities as well just off the mainland at Islas Murcielagos. Often overshadowed by Cocos’ legendary reputation, the diving off Costa Rica’s west coast is spectacular in its own right. The thriving dive town of Playas del Coco in Costa Rica’s northwest is a mecca for divers from all over the world. It provides an enchanting base for exploring the reefs and wrecks off the Guanacaste provincial coast.

Howler monkeys chatter in the trees above rustic bars and makeshift curio stalls. Iguanas skitter across the sidewalk, and the sea laps endlessly upon a shore stained black by volcanic sand. A picturesque mountain peak overlooks the town. Flowering hibiscus plants throng the roads leading to the foothills. Every evening the sun sets spectacularly over the glassy ocean. It’s a place where days turn seamlessly into weeks, not least of all because of the amazing dive sites just a short distance from shore. Playas del Coco is most famous for Islas Murcielagos. This small chain of islands is an hour out to sea, and home to a resident population of bull sharks. 

Diving Islas Murcielagos

The day that I visited Islas Murcielagos, which translates to ‘Bat Islands,’ the sea was rough. By the time we reached the islands, the surf was breaking fiercely over the jagged cliffs and outcrops. I was beginning to feel a little jittery. Searching for bull sharks can be intimidating at the best of times, and the less-than-perfect surface conditions did nothing to calm my nerves. The dive briefing was necessarily serious. Unlike elsewhere, dive operations have not conditioned the bull sharks of Islas Murcielagos through baiting, feeding or chumming. Instead, they are wonderfully wild apex predators and divers must respect them accordingly.

Because the current at the islands is typically strong, the divemaster instructed us to reach the seafloor as quickly as possible through a negative descent in order to prevent being separated or swept off course. He told us to stay together once we’d reached the seafloor. Finally, he told us to follow behind at all times, to be aware, if we saw the sharks, not to attempt to touch them.

Then it was time. One moment, we sat on the edge of the boat, ready to back roll into the water. The next, I was finning down towards the divemaster waiting on the bottom. In the mad rush to get down, it took a few moments to become aware of our surroundings. Little by little the dramatic volcanic landscape of the dive site known as the Big Scare began to materialize around us. Visibility was poor, perhaps 18 feet in a location where 100 is possible. But somehow, the murkiness lent the dive a heightened the sense of adventure and kicked up the adrenaline factor several notches. 

The volcanic topography of the Big Scare features striated slopes of lava, frozen in mid-flow. These stretch away on either side into the looming greenness that constituted the edge of visibility. I stared into the soupy distance, willing a shark to materialize out of the gloom. I so desperately wanted to see them that my imagination began to conjure up indistinct shadows. Then, suddenly, one such shadow didn’t disappear. Instead, it got darker and more defined until I knew that it was undoubtedly a bull shark.

The animal was simply enormous. It easily measured 10 feet from the tip of its blunt, wide nose to the end of its powerful tail. Bull sharks are among the most impressive of all shark species. Their sheer bulk and the purpose with which they move through the water lends them a presence that can be neither ignored nor denied. That first shark skirted around our group on the very edge of visibility. It teased us with its closeness but kept its distance. 

Strangely, given the circumstances — being surrounded in limited visibility by sharks that have a dangerous reputation — my initial nerves dissipated when the first shark arrived. The shark circled us several times and then disappeared back into the green. It showed significantly less interest in us than we had in it, and we continued on our way, swept along by the current. We saw several more sharks on that dive. Some came close enough to allow us to see their skin, lined with the white scars of past injuries, and their small, intelligent eyes. In the end, the poor visibility didn’t affect my enjoyment of the dive. I’ve seen footage of dives at the same site in good visibility — and they are predictably spectacular. But sometimes, the thrill of what you don’t see is a heady thing. 

Why the sharks have taken up residence at the islands is not known for certain. The deep water and remote location does mean that there’s plenty of prey that’s absent closer to shore, however. Manta rays and passing pelagic fish, including marlin and sailfish, also frequent the sites. Although the bull sharks are here year round, rough waters in the Gulf of Papagayo for half the year mean that dive boats only visit between May and November. The dive sites there are deep, ranging from 60 to 115 feet. This depth combined with the strong currents and the need to descend rapidly means that this area is only suitable for those with an advanced certification or the equivalent.