Green Rock is a hidden gem among dive sites around Koh Tao. It lies just North of Koh Nang Yuan island and is often overlooked as a dive site. It is a staff favourite at Sairee Cottage Diving. With such diverse diving on offer, Green Rock is sure to excite many divers. It offers deep pinnacles that can be explored, as well as fantastic swim throughs, a ton of macro life and an easier, shallower shore dive option for new divers. For those seeking a bit more adrenaline, we can venture into the “trigger pit”. This is where the titan and yellow margin triggerfish have their nests. In May it is mating season and they are very particular that this part of Green Rock belongs to them!

Green Rock Dive Site Map

Green Rock Dive Site Map

As we more up, we are the only boat at Green Rock.

On our dive at Green Rock, we decide to descend down the deep line. The current was present, but not too strong. We used the line to descend to the bottom of the smaller, deeper pinnacles. All of us wanted to go and see what lies on the deeper slope of the dive site.

It does not take long to spot the first moray eels hanging out together. Right after, a massive marbled grouper dashes into a little cave to hide and wait for prey. The visibility drops a little as we reach our maximum depth of 29m. On the untouched parts of the site we find whip coral in pristine condition. Xeno crabs are hanging on to them, gently swaying in the current. Just before we decide to turn and swim up shallower, we notice two eyes buried in the sand. A massive jenkins whipray is hiding just below the sand. What a fantastic sighting!

A few titan triggers guard their nests as we watch two anemone shrimp slide around inside their soft anemone on the fringes of the trigger pit. Lots of nudibranchs are dotted around the floor as we are making our way to the main pinnacle.

We proceed to glide through the various swim throughs Green Rock has to offer. Inside we pause to see ghost shrimp, banded, yellow & janss’ pipefish. A little further up we see the other fun dive group from our boat. It is Gal, our head divemaster.

“He points at something so small, I can barely make it out.”

He sees me and seems very excited about something. He then signals to follow him. My group and I follow him for quite a while. Eventually he stops and in his signature way, points at something so small, I can barely make it out.

I get closer. It is a tiny nudibranch in the Flabellina family that I had never seen before. Maybe 9mm long. This is the nerd category of diving that we get so excited about! One of the reasons Green Rock is in my top five dive sites around Koh Tao.

Dive Green Rock

We highly recommend Green Rock when visiting Koh Tao for scuba diving. It is a part of our weekly schedule and when conditions allow we sometimes dive it in the afternoons instead of the busier dive sites. Thursday mornings we dive Green Rock. We dive here all year round, except when waves are too big or there is a strong current. Because it is exposed to the North, we can get currents at Green Rock all year. This makes for a fun experience as Koh Tao is known for not having currents. If you are here in May, we recommend checking out the “trigger pit” – It is a lot of fun to watch the triggers fight and protect their nests..

Have your own experiences you would like to share about Green Rock? Please do so in the comments below!

About the Author

Dive Instructor Lionel blowing a bubble ring.Lionel quit his job in 2013 and bought a one way ticket to Asia. The plan was to travel for 3 months, then find work and live in London as an expat. On my travels I fell in love with diving and I am currently a Scuba Diving Instructor on a tiny island in Thailand. I also write on my diving blog over at down to scuba.

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