Thailand is one of the few places on earth where giant Manta Rays are frequently seen. These amazing creatures with wing span’s in excess of 6 meters, frequent the waters around the Similan Islands year round, and are also frequently seen at a variety of Phuket’s local dive sights throughout the year. Manta Birostris to give them there official name are part of the larger Mobulidae family, and are largely pelagic, spending most of their lives out in the open ocean. The Manta Ray is a filter feeder, feeding mainly on plankton and small fish, but have also been seen feeding on fish eggs during spawning season.

The Manta Ray uses its two protruding frontal lobes to help push its food towards its enormous mouth, where thousands of tiny teeth wait to filter its food. The Manta Ray only has two known predators, sharks and man. It is not uncommon to see Manta’s with scaring on the rear of their bodies caused by shark attacks. It is believed that the Manta Ray will defend itself with its enormous powerful wings, which it will use to hit the attacking shark. The more worrying concern is that of commercial fisheries catching Manta Rays in their nets, which is a practice still occurring all over the world. The Manta Ray meat is often ground down and sold on as a fish based product.

Although mainly pelagic, these beautiful rays often congregate in large numbers around the western ridge of the island of Koh Bon, situated to the north of the Similan Islands, where it is not unusual to see up to 10 individuals at one time. This large gathering has always been thought to occur for cleaning purposes, in which reef fish will come and remove any parasites which have attached themselves to the Manta’s body.

Another theory behind this gathering is that it is part of a mating ritual, and the males are trying to attract females into mating.

Manta Rays are ovoviviparous, which means there young which originally develop inside eggs within their mothers body, will hatch out within their mother before being released out into the water. Manta Rays usually give birth to two pups after a gestation period of thirteen months.

Although extremely rare, some scientists have actually witnessed female Manta Rays breaching the water and ejecting their young offspring in midair. Although this phenomenon is very rare, Manta Ray’s are commonly seen breaching around the Similan Island for cleaning purposes. This behavior has been likened to whales and dolphins who will breach to remove harmful dermal ectoparasites, but also to exhibit playful and dominance behavior.

The colourings and markings of Manta Rays are completely unique to each individual. The most common patterns are a darkish black/blue colouring on the top, with a pale white underbelly, with scattered black dots which are thought to increase with age. Every once in a while though, sightings of completely black individuals are seen, and even more rare are the white albino Manta’s, each of which have been seen in recent years at the Similan Islands.

When diving with these gentle giants, divers must adhere to certain guidelines, as outlined below.

• If Manta’s are present, enter the water carefully to avoid scarring them away.
• When first spotting a Manta Ray, Check AIR and DEPTH gauge.
• DO NOT CHASE THE MANTA”S, they will leave the area.
• NEVER, UNDER ANY CIRCUMSTANCE TOUCH THE MANTA RAY.
• If you follow the Manta, please be aware of your depth.
• DO NOT TRY AND CORNER THE MANTA RAY”S

During my many years diving within Thai waters I have been lucky enough to have many magical encounters with Manta Ray’s, and on almost every occasion I have seen divers disregard these simple guidelines, with often almost disastrous consequences. I have seen a diver leave the rest of his group at 5 meters and follow the Manta Ray down to 30 meters plus. I have seen people try to ride them, which resulted in a very angry Manta Ray leaving the area, and spoiling the enjoyment of viewing these fantastic creatures for everybody else.

I have seen divers follow the Manta Rays from 20 meters to 5 meters then back down to 30 meters, and then realizing that they only had 20 bar (300 psi) left. From all of the fabulous creatures as my time as a diver, Manta Ray’s are my favorite. Of course its nice to see Whale Sharks , turtles , leopard sharks etc etc, but the giant Manta Ray is a very special creature. Often when encountering Manta Ray’s they seem to be enjoying the experience as much as you are, they will often circle around and come back to you time and time again, and seem to enjoy the feeling of the divers exhaled bubbles on the underside of their bodies. With trips departing everyday during the high season, the Similan Islands are the place to be, if you want to have a memorable encounter with one of the oceans most fabulous creatures.    

• Koh Bon
• Similan Islands
• Richelieu Rock
• Racha Noi
• Hin Daeng and Hin Muang