More commonly called San Antonio after its only municipality, Dalupiri has good beaches and clear water, and is close to the mainland. Such is its appeal, this is the kind of place where you can expect to get stranded longer than you planned.
There is a growing range of chilled-out accommodation options on the beachfront. Electricity is off from 6am to noon each day, so rooms can be hot if there is no breeze.
The neighbouring forested island of Capul, to the west, has an even slower pace of life and is definitely worth a day trip, or an extended stay. Or head to the remote but idyllic Seven Islands for pink-sand beaches and total isolation.