The highlight for me at the resort we stayed at on Koh Samui was a small island just off the hotel beach. Mad Lang Island (Google Maps below) was about 400 meters off the coast, and during low tide, you could walk to it. Ocean and I paddled our kayaks over the island a couple of times. The beach was full of plastic garbage and with rocks and thick vegetation, it seemed to be impossible to explore the interior of the island. I finally climbed a large boulder that led to a trail on the backside of the rock. I followed the trail to the other side of the island, and it led to an abandoned Buddhist Shrine (below). The shrine is located on the highest part of the island and offers some beautiful views. Nāgas are associated with water deities and protect sailors and fishermen from storms, so it is appropriate to find this shrine on a small island in the Gulf of Thailand. The trail continued around the island coming back to beach. I am surprised that it is unmarked and not kept up by the resort. It would be a fun project to improve the trail, add directional signs and provide information at the shrine.
The statue depicts a seven-headed serpent protecting a reclining Buddha. In Buddhist theology, “Mucilinda” is a “nāga” (half-serpent/half-human divine being) King Mucalinda provided shelter to the Buddha from a storm by covering the Buddha’s head with his seven snake heads.
Bill's Blog 
I’m in Koh Samui right now! So glad I came across your blog. Will definitely keep reading. How cool are you and your family!