Continued: ALONG THE RIVIERA MAYA

Ruin with a View

Seventy miles south of the airport is one of Mexico's most important archaeological sites, Tulúm, the only Mayan city built on the sea. It's also home to a dizzying array of small inns and some of Riviera Maya's finest beaches. Tulúm is also coping with a decade's worth of poorly regulated development and as many as a dozen hotels built close to the ruins may be torn down for encroaching on national park land. Still, Tulúm boasts off-the-grid chic that lures a young and international crowd for simple cabana comforts and Buddha Bar aesthetics.

The ruin itself is perched on a rocky bluff and is one of the few places along the Yucatan coast with any topographical character. Small coves are tucked into the rocks immediately below El Castillo, and a milelong stretch of excellent beach that extends south to another series of rocky bluffs is directly in line with the town, which sits a mile inland. This stretch draws locals, and the ambience can be festive. Follow the coastal road just beyond the well-liked restaurant Zamas Que Fresco, and the sand continues -- unbroken, unnamed -- for miles. Most beach access is from the paved road and in many areas requires walking through one of the many small, casual hotels.

Development ends at the 1.5-million-acre Sian Ka'an Biosphere, a national park and UNESCO World Heritage Site. While the park is focused on jungle walks, mangrove lagoons and unexcavated ruins, the 22-mile Boca Paila peninsula is fronted by a ribbon of fine white sand that will indulge your most escapist Robinson Crusoe fantasies. Beware the road heading south, the worst of which is best left to all-wheel-drive vehicles.

Where to stay: Accommodations in Tulúm range from high-style roughing-it to dank hovels. Expect little in the way of air conditioning, phones or TVs, and be prepared for occasional mosquito invasions. Charming Piedra Escondida is an eight-room inn of two-story palapas overlooking a placid cove raked clean each morning. Hammocks sway on the porches; a small restaurant serves inexpensive meals. From $105, including tax and breakfast ($165 high season); (011-52) 984-100-1512; piedraescondida.com.

*Unless otherwise noted, all nightly rates are per room, double-occupancy, and do not include meals or taxes.

San Diego-based David Swanson is a contributing editor to National Geographic Traveler and writes the "Affordable Caribbean" column for Caribbean Travel & Life magazine.