Similan and Surin Islands are both national parks and very popular attractions. Crystal clear water, white glittering beaches, and landscapes that usually can be found only in postcards.
Snorkeling trips are organized on both islands and traveling happens by speedboats. These voyages take about 45-60 minutes per direction, depending on the air and sea conditions. More information on snorkeling trips
If you just want to relax and enjoy the tranquility, staying at Surin Island is possible. Accommodations take place in tents or bungalows on the beaches. The island has electricity, which is cut off in the evening and connected in the morning. Hence there is no light in the evenings other than the stars and the moon. At night you can hear and experience the sounds of the jungle, and perhaps see a few familiar monkeys. This island also works for a social media detox as the internet connection is most likely going to break-up.
Enjoy offline life for one night!