Lighthouse trek.
By far the most popular trek is Saracen/Sandy Bay – Lighthouse – Military beach – Lazy beach – Saracen Bay [ – Sandy Bay]

Lighthouse is a military base on a high plateau overlooking the Gulf of Thailand. It consists of a few houses, a tall lighthouse and live canons. It is Cambodia’s defence line against military incursions from the west side. Bring $1 pp to be able to climb the lighthouse – it is worth the money and trouble – the views are astounding. The canons are live, but intended for military purposes. Military beach is located underneath the high plateau and houses several very official looking buildings with flags. With favorable wind the water is crystal clear. It is an excellent spot for swimming and cooling down. Coming from the lighthouse side you need to walk all the way to the other end of the beach. You will see a small opening in the jungle leading to a path up the hill. Follow that path keeping the sea on your left hand side and eyes open for various surprise stone carvings.  On our last visit the area just before the Lazy Beach was under construction. You need to find a path which takes you down from the hill to Lazy Beach. It might require a bit of experimenting. Lazy Beach is a renowned area for its beautiful beach and snorkeling. Good place to take a rest, have a drink and prepare for the stretch back to Saracen Bay. The path back to Saracen is clearly marked and it is easy walking about half an hour.