The sole reason that diving has become popular in Trang are two pinnacles that lie approximately 25 kilometers Southwest of Koh Rok.
Hin Daeng (red rock) and Hin Muang (purple rock) offer everything a diver could want, from dramatic walls and big fish action, to lush tropical underwater gardens.
Hin Muang
Hin Muang, located just a few hundred metres from Hin Daeng, lies completely submerged.
What surprised us the first time we explored the rock was the incredible amount of marine life that clung to the rock.
It is as if the rock were located in another ocean and not just a short distance away from the relatively barren Hin Daeng.
The name derives itself from the thick purple growth of soft corals that are everywhere.
The rock itself is approximately 200 metres long and less than 20 metres wide, and is shaped like an immense loaf of bread with steep, vertical sides and a rounded top.
The walls are decorated with large sea fans of red, white and orange. Clouds of glass fish, or silver sides, school around the fans and rocky out-croppings. Carpets of anemones cover the shallower sections of the pinnacle.
One July, the water was so transparent and the sea so smooth that I could see clearly the splash of someone throwing the dregs of their coffee overboard-puffy white tropical clouds as a back-drop from a depth of over 45 metres.
Whale Sharks are one animal that we see repeatedly around these pinnacles and this year we saw them on almost 70 percent of our trips there.
On many occasions we swim with gray reef sharks in the deep blue water off Hin Daeng and Hin Muang.
This is the only place in Thailand where I have seen more than 10 gray reef sharks together at one time. In fact, even at the Burma Banks this type of shark is rare.
Gray reef sharks are full-bodied sharks, powerful and sleek, and are often confused with black tips because of their similar markings. However, unlike their cousins, these sharks are true pelagic animals, and swimming with them is a stirring, emotional experience.

Source: ©Siam Dive n' Sail