Belize, Placencia open placemark
This is a totally laid-back seaside town, with a pristine sandy beach on a long, narrow peninsula in SE Belize.

It is is well worth the trip to get there [4-5 hours from Belize City, but now daily domestic flights are available.

Facilities are simple but comfortable. Apart from just lying on the sand, you can do various water sports, fishing, bird watching, manatee watching [!] and jungle excursions in the Cockscomb Basin Wildlife Sanctuary.

If you want more action [especially diving], try the Cayes; resort-oriented Ambergris Caye, or relatively low-key Caye Caulker. Both are good bases for diving and snorkelling off the world's second greatest barrier reef.

The best time to go is Nov - May [the dry season, but peak time]. July to November is cheaper, with a risk of storms.