Railay Beach is mostly known for its beautiful beaches, majestic rock faces and rock climbing. Depending on how adventurous you are there is also a remote Railay Beach Lagoon that you can access but it takes some scrabbling to get to. While walking from Railay East to Railay West along the SE edge there is a prominent trail made with rocks and cement. About mid-way between the two beaches there is a sign for a lagoon. The trail starts promptly, climbing straight up. I would suggest wearing shoes and not flip-flops but there were many people wearing flip-flops which is asking for injuries.
The trail climbs about 500ft in less than half mile. There are hand lines to assist you while you are climbing. Once you reach the top of the first climb the trail diverges, if you take the left trail it will lead you to a look-out of Railay East and is spectacular. The look-out is roughly 300ft or 100meters. If you decide to continue to the lagoon, then you start to descend and you have to climb over several rock ledges. The rock ledges are quite technical and have hand lines to help you descend but if you have a fear of heights, this may not be the trail for you.
There are three rock ledges that you have to descend. Once you are able to get to the bottom, you reach the lagoon which is fed by ocean water. It is important to monitor the tides so that you can get there at high tide. If you arrive at high tide then you can swim in the lagoon. Unfortunately, after two attempts, I was never there at high tide. But I was able to take a trail to the opposite side of the lagoon and explore a cave system.
The lagoon is an oval shape and is surrounded by diverse flora and fauna. Depending on the time of the day, the sun will penetrate through to the lagoon. I would avoid going there at night or leaving in the dark as the trail is very technical. Even if you have a head-lamp, this trail is better suited during the day. Have fun!