When arriving (by boat of course) to the small archipelago Mu Koh Surin, the view is stunning. You feel like you have arrived at the setting for these advertisements seen for Bounty chocolate bars and other goodies peddling images of snow white powdery beach sand and palm trees billowing in a gentle breeze.
Mu Koh Surin is a national park located in the Andaman Sea, 80 minutes by speedboat from the coast. If you do not bring your own tent, basic accommodation (tent or large bungalow) can be provided by the national park on Koh Surin Nua. Due to the limited capacity, it is highly recommended to call in advance if you plan to go over a long weekend where many other often get the same idea. Since there is only one speedboat “ferry” per day, which departs from Kuraburi, you should secure your ticket in advance unless you have the cash to rent you own boat.
Once on the island, there isn't much to do apart from enjoying the sights. The small shop and restaurant close at 8 PM while lights are out by 9 PM. Koh Surin is not a party island like Koh Samed or Koh Phangan – people go to bed (sleeping bag) early and get up early.
There is a nature trail (2+ kilometers long) between the two camps on the island, but most visitors focus their activities on the sea. The bays have wonderfully clear water and coral reefs can be reached after swimming 25-30 minutes. A park ranger told me that corals on lower water depths were killed a couple of years ago when a warm ocean current persisted for too long. But there are still many fish even at the lower water depths.
If it is not up your alley to have to swim 30 minutes before you can start diving to watch corals, then day trips can be arranged where long-tail boats will take you to good snorkel locations.