If you are visiting Koh Tao to dive, chances are good you will get to visit Twins. This small dive site has a lot of things going for it!
It's easy to dive and normally experiences little to no current. It's suitable for most levels of divers, as it has both a shallow and a deep area. There's a massive underwater sculpture park called Buoyancy World, which is great for both practicing your skills and checking out the underwater art. And most importantly, there is a lot of marine life diversity!
Located just west of Koh Nang Yuan, the dive site is made up of 3 pinnacles at 3 different depths ranging from 5 to 18 meters. If you swim towards Nang Yuan from the shallow pinnacle, there is a large section of healthy reef where some marine life can be found. On all other sides however it's surrounded by sand, meaning that the pinnacles acts as a natural refuge and hunting ground for lot's of different species of fish.
Because of this, Twins probably has some of the highest concentration of marine life species anywhere around Koh Tao. Beneath the rocks you'll find bluespotted ribbontail rays, moray eels, groupers and shrimp cleaning stations. Around the reef there's normally plenty of titan triggerfish, batfish and porcupinefish. If you're lucky you might spot turtles or banded sea snakes here too!
If you swim out into the sand surrounding the dive site you might be in for a special treat. Chevron barracudas sometimes hang out in massive schools! They are also sometimes joined by solitary giant barracudas. There's also lots of marine life on the sandy bottom so keep an eye out for cool shrimps, nudi branches and other colorful critters.
For these reasons, combined with the fact that it's an easy to reach dive site even in rough weather, Twins is one of the most popular sites to dive around Koh Tao. Due to it's size, it can sometimes feel a bit busy with several dive schools visiting the pinnacles at the same time, especially just before and after noon. But even on a busy day it's still a lovely dive, with plenty of things to see!