Topic: Getting back to Ao Nang from Railay

Hello, I wonder if you could give me some advice. My husband and I are staying in Ao Nang over the Christmas/New year period, but Im really wanting to spend some time in Railay through the day and into the night, as Ive heard there are some good reggae bars there. What would be the latest time we could get a boat back to Ao Nang in the evening, and if we missed it, is it possible to spend a night sleeping on the beach? Or are there other ways of getting back? Cheers, Clair