If you are visiting Koh Lanta in Thailand you should definitely consider a trip to Koh Rok. It’s a tiny island with absolutely beautiful beaches and chrystal clear blue water. You can buy a ticket with a speed boat to this island which includes lunch and extra stops for snorkeling.
When the rest of our party drove off to dive nearby we decided to stay on the beach for a little longer. We had three small children with us and the beach looked so inviting we preferred to stay here. On the way back to Lanta, our boat stopped on the other side of the island for some off shore snorkeling, so we got some of that too.
Especially during lunch you should keep an eye out for giant lizards that live on the island. They are not scary but I wouldn’t go too close.