THE INSULAR ARCH OF REVILLAGIGEDO is part of an underwater volcanic structure called Las Montañas de los Matematicos. Some of its peaks, including those of Roca Partida, Socorro and San Benedicto, reach the surface of the Pacific, way out west from the coast of Mexico. Solmar V, www.solmar.com
The waters lapping the island of San Benedicto are the kingdom of the great oceanic manta rays. It is here that these creatures approach divers and do their utmost to initiate some gentle interaction with them.
This is a unique experience. We all know how cautious and shy most fish are when divers are under water, particularly if they dive with open-circuit equipment and emit bubbles and noises. Mantas elsewhere in the world are as shy as any fish. Yet, for some reason we don't understand, those of San Benedicto seek out divers and perform enchanting dances that finish only when we have too little air left in our tanks.
This manta population has often been mentioned in the past with reference to Socorro, but in reality the rays should be associated with San Benedicto - Socorro just happens to be the naval base where your passport is checked, and the diving there is nothing special.
Our unbelievable cruise was aboard Solmar V, a luxurious and comfortable liveaboard that departs from the harbour of Cabo San Lucas in Baja California. The manta rays are part of an itinerary offered between November and April, at the end of the hurricane season. Wave after wave, mile after mile, Solmar V ploughs south through the Pacific Ocean to reach this remote and incomparable dive spot.
The manta rays that can be seen here are the most empathetic of animals, with their natural grace and beauty, the flowing movements, the somersaults and the looping runs. They combine the elegance and nimbleness of a teenager dancing in a classical ballet with the power and strength of a jet fighter.
And they search out divers, stopping 2-3m above our heads to enjoy the hydro-massage provided by our exhaust bubbles. They literally "thrill" when the fragile bubbles of air break against the white surface of their bellies.
Normally direct contact with marine life is a bad idea. Here it is hard to avoid.
An enormous sadness pervades us as we are escorted to the steps of the boat by two or three giant mantas who cannot believe that the fun is already at an end. Their charming and intelligent eyes scan the water disappointedly before they acknowledge that the game is temporarily over.
From the bridge of the boat, we can see the rays' dorsal fins ploughing the surface as they patiently await our return.
We spent several hours a day in the warm water of San Benedicto, and the mantas never once missed our appointment.
• Manta rays can leap up to 2m out of the water - smacking back down against the surface removes parasites and dead skin.
• An old myth had it that mantas could drown swimmers by wrapping around them. Untrue!
• Manta rays have a similar feeding system to blue whales, basking sharks and whale sharks.
• The word "manta" is Spanish for blanket.
• The manta's entire skeleton is made of cartilage, giving it a wide range of motion.