The Cave of the Sleeping Sharks Isla Mujeres

Apart from its natural beauty, Isla Mujeres seems to cast some kind of spell on animals’ behavior. A good example of this is the gathering of whale sharks in the blue waters of the Caribbean Sea in the area. The point is that whale sharks are solitary animals but hundreds of them gather near Isla Mujeres during the summer season to feed from the rich plankton and algae in the area.

Another amazing phenomenon takes place at the Manchones Reef at about 65 to 100ft underwater (20-30mt). If you get close enough to the cave called “Los Cuevones,” made up of coral formations, you will be able to admire the magic view of nurse sharks sleeping with their eyes wide open. This wouldn’t be surprising at all if we didn’t know that sharks never sleep. They need to keep in motion to be able to breathe. If they stay still, they die.

In 1969 Carlos García Castilla, a lobster diver from Isla Mujeres, was diving for work when he felt intrigued by a strange phenomenon.  He saw that sharks entered the cave but he never saw them come out of it. He got closer and got astonished by the image. The sharks remained still with their eyes wide open. He then contacted the oceanographer and journalist Ramón Bravo. Mr. Bravo was quite skeptical about the news but decided to take a look at the cave. So he took his snorkeling gear and his camera and dove to the famous cave. Bravo saw the sharks resting at the bottom of the cave in a state of dormant inactivity and called Dr. Eugene Clark to study the phenomenon.  Dr. Clark settled on the island and pursued an investigation to find out the biological causes of such a strange behavior. She finally concluded that these sharks take oxygen from the fresh water bubbles by standing still against the current. They are not completely asleep because they follow the divers around them with their open eyes. From then on, Isla Mujeres became the selected site of oceanographers and scientists. Even Jacques Cousteau moved to Isla Mujeres for a couple of weeks to study the sleeping sharks.

The cave was renamed as “The Cave of the Sleeping Sharks” and became one of the main attractions of Isla Mujeres. The most common shark type that can be found is the nurse shark; but lucky divers may spot tiger sharks, mako sharks, bull sharks, lemon sharks, manta rays or black tip sharks. Only experienced divers can access the cave due to its location deep below the sea surface. The experience is incredible and the most adventurers cannot miss the opportunity of visiting it.

Can you imagine the adrenaline of swimming so close to these marvelous and dangerous fish? Of course you will be accompanied by a professional diver who will give you all the necessary tips to enjoy the tour to the most. Please, remember to do exactly what your guide indicates so that you can experience a safe tour.  If you are planning to visit Isla Mujeres sometime, start taking your snorkeling lessons! The Cave of the Sleeping Sharks is a tour not to miss.

Cecilia Vittori