If you haven't gone coastal in Mexico lately, then you're really missing out.
Whether your tastes hew to the calm Caribbean or the rugged Pacific, Mexico offers 6,000 miles of coastline to choose from. But beyond the popular destinations of Cancún, Cozumel, and Acapulco, these areas are less discovered. Today, there're loads of new seaside development along the Riviera Maya (Caribbean) and around Puerto Vallarta (Pacific), and a world of activities for enthusiasts of all kinds.

Mexico, for all its vacation seductions - the beaches, the siestas, the muchas margaritas -- never said "road trip" to me. Until the Riviera Maya emerged. The 100-mile Yucatán coast south of Cancún boasts nature parks, Mayan ruins, the lively port of Playa del Carmen, and, of course, mile after mile of white-sand beaches. As recently as 1995, only 1,400 hotel rooms existed here. Now there're a whopping 24,000, just 3,000 shy of Cancún - Mexico's number-one tourist destination. To say business is booming in these parts is an understatement. So I took to the road to get a sense of the place.

Highway 307 skirts the shore from Puerto Morelos to Tulum in a north-south corridor marked by lush jungle, overlarge billboards, and the fortresslike gates of hotel compounds. Nature and commerce are clearly in competition here. The two dovetail in a string of government supported "eco-parks," natural preserves specializing in fun, adventure-light re-creation. At the latest, Aktun Chen, I hike the cool subterranean caves of porous limestone, alive with bats, underground pools, and endless dark nooks (funny how I tailgate my guide here). Beachside, the recently opened Tres Rios combines easy-going beach life and natural wonders. I grab a fat-tired bike and ride the sand roads to the Cenote Aguila river, where I don a hyper-buoyant life vest and snorkel gear and float on the freshwater river's natural current out to sea, past fish-rich mangroved shores. Later, as I recharge in a hammock before tackling the gorgeous surf in a kayak, I watch a group of horseback riders galloping at breakneck speeds down the shore.

I could be content right here, but there's lots more ahead, so I'm back on the blacktop. As I travel this stretch, I notice that Riviera Maya hotels come in three styles - luxury, all-inclusive, and independent hideaway - which roughly correspond to north, middle, and south shores. Maroma Resort, 20 minutes south of the Cancún airport, first put this region on the map and was recently acquired by Orient-Express Hotels. The romantic, whitewashed Moorish compound has expanded with 22 additional rooms and a new spa. It's the Riviera Maya's gold standard against which a crop of newcomers aim to compete, including thatch-roofed Ceiba del Mar, where a porter delivers coffee in-room each morning and the spa offers holistic massages. Ikal del Mar takes the boutique hotel concept to the sea with double-wide chaises for two at the beach, massage tables draped in mosquito netting, and sleek, jungle-shrouded casitas with private plunge pools. Not to be outdone, Paraiso de la Bonita antes spacious suites, the destination-worthy cooking of chef Fabrice Guisset, and a lavish Thalasso spa offering novel massages under a rain of warm seawater.

Midway down the coast near the port of Playa del Carmen, I check into the Occidental Grand Flamenco Xcaret, a massive, Spanish-owned all-inclusive with access to the neighboring Xcaret eco-park. Like the park, it has Mayan ruins on site, a lovely beach cove, and woodland wildlife. Guests divide themselves between the popular swim-up bar (Americans) and the topless beach (Europeans).

Almost a third of Mayan Riviera visitors hail from Europe, bound for the distinctly Euro-accented Playa del Carmen, where shops, bars, and cafes plaster the pedestrian-only Avenida Quinta. My perfect Playa evening starts at the Blue Parrot's beach bar (where the bar stools are swings), pro-gresses to authentic Mayan food at Yaxche, and ends at the Deseo Hotel. Its rooftop lounge screens vintage Mexican westerns on a wall for patrons sprawled under the stars on white, cloudlike daybeds.

South of Playa the road narrows to two undivided lanes, well trafficked by buses bound for the Mayan seaside ruin of Tulum. The area's modest hotel zone attracts urban-escapees with small, affordable, and mainly unplugged cabana retreats ranging from $8-a-night hammocks to $200 rustic-chic cottages. I select the solar-powered Las Ranitas, where decoratively painted guest rooms and a shaded dining patio are perched just five steps above the powdery beach.

As yet, the development drive hasn't consumed the entire shore, leaving a few untrammeled quarters worth seeking out. Restaurant Oscar y Lalo, seven miles north of Tulum, serves whole grilled fish under the shade of its palms, and provides daylong access to the pristine Soliman Bay. Yakul, just north of Akumal, is a river-fed ocean lagoon teeming with fish. It's similar to the nearby eco-park Xel-Ha, but without the tour mobs. The ruins of Coba, a 40-minute drive inland from Tulum, are another great alternative. For about $2.50 you can rent a mountain bike and do a two-wheeler road trip around the vast ancient city, which includes the tallest temple in the Yucatán. Its ancient limestone-paved roads plunge mysteriously into the jungle, bound for raw and remote locales. This signals the end of the road for me. Time to get back to four wheels, a couple of Co-ronas, and one colorful sunset.

Tourism-wise, Puerto Vallarta was founded on the Elizabeth Taylor-Richard Burton affair. In 1963, Burton filmed Night of the Iguana here, trysted publicly with Taylor when both were married to others, and drew paparazzi. Romantics the world over took note. Forty years hence, the once sleepy fishing port has grown to 250,000 speeding motorists, time-share sellers, artists, and optimists of every stripe.

Witness Hurricane Kenna, which lashed PV last November, whisking statues from the waterfront seawall-cum-sidewalk known as the malecón, and depositing them hither and yon. On the cusp of high season, which was just a month away, would PV get it together? "We won't be open for breakfast today, amigo," one restaurateur claimed. "Maybe by supper time!" Indeed, within two weeks, 90 percent of its properties were operating anew, living proof of PV's enterprising spirit.

"Vallarta's got a very unique energy," observes Jorge Rubio, who designed and runs Terra Noble, a spa built entirely of recycled materials in the hills above town. Castoff tires form stairs that lead to thatched massage huts. Visitors often stop at Terra Noble to snap panoramics of Bahia de Banderas, the Pacific's largest bay, and the Sierra Madre mountains ringing town.

One scan of the shore and it's clear that resort growth is headed north to Nayarit, neighbor state to PV's Jalisco. A few years back, the Four Seasons Punta Mita stationed an exclusive enclave 26 miles north of town, establishing a distant bookend on the bay now being filled in by others. Luxury hotelier Rosewood is constructing a resort to open next year. And this past spring, swanky Grand Velas debuted its upscale all-inclusive compound in Nuevo Vallarta. Sporting a plastic bracelet to indicate residency, I park my wallet in the in-room safe and indulge in everything from poolside margaritas to the minibar snacks included in the room fee. Spacious quarters, a tri-level infinity pool, and a deluxe spa with hydrotherapy pools, waterfalls, and ja-cuzzis highlight the stunning property.

On the recreation front, golf has exploded since Vista Vallarta opened two years ago with 18 holes designed by Jack Nicklaus and another 18 by Tom Weis-kopf. An amphibious golf cart accesses the island-stranded third hole on Nicklaus' Four Seasons Punta Mita course.

Seeking a no-pain/huge-gain adrenaline rush, Canopy Tours' safety-harnessed and pulley-clutching riders zip down cables strung between trees. Not without an into-the-air leap of faith, my initial screams of terror gradually morph into the bellows of a high-tech Tarzan as 10 progressively lengthening lines work up to the 750-foot "Big Enchilada," crossing the Tomatlan River at jungle-blurring speeds that wind- shear my baseball cap.

For all of its out-of-town lures, what's greatest about Puerto Vallarta is the town itself - the street performers on the malecón, the first-Communion kids on their way to the cathedral, the artisan stalls, the Mexicana-meets-minimalist Premiere Hotel, and especially the restaurants. At the newly opened Los Xitomates, chef Luis Fitch, wearing toque and high-tops, merges Mexican, Caribbean, and Continental food in dishes like scallop carpaccio. The two Germans running Trio serve cilantro-ginger calamari and spiced quail. And the casually named DaiQuiri Dick's issues some of the best meals in town (think lobster tacos), thanks to chef Rafael Nazario, who gained kitchen acclaim at Hugo's in L.A.

Nazario, also a musician and cookbook author, escorts me to La Bodeguita del Medio for mojitos and the brassy sounds of its Cuban house band. Afterward, we hit De Santos, a rooftop lounge where young lovelies drape across daybeds under the star-filled sky. The owner tells me he's opening a nightclub in New York's trendy Meatpacking District. Puerto Vallarta taking it to Manhattan? Now that's truly happening.

is a Chicago-based writer and contributing editor for American Way magazine. Her work has appeared in National Geographic Traveler, Travel + Leisure, and Shape.

Graciela Cattarossi is a Florida-based photographer whose work has appeared in Travel + Leisure, Travel + Leisure Golf, and Conde Nast Traveler.