Dirt and paved roads etch Baja's two coastlines, leading to primo surf breaks and languid lagoons. The Transpeninsular Highway parallels the Pacific coast in northern Baja and the Sea of the Cortez in the south, passing windswept beaches littered with driftwood and shells at San Quintín and breathtaking vistas at Bahía Concepción and other aquamarine coves and bays along the Sea of Cortez. Most coastal towns have beaches filled with families swimming in shallow waters—Playa Pichilingue and Playa Coyote in La Paz are quintessentially Mexican in style and amenities (umbrella and chair rentals, cafes in the sand serving oysters Diablo and whole fried fish). Los Cabos has precious few beaches offering safe swimming, though some resorts in the Corridor provide man-made coves for swimming. Playa Médano in Cabo San Lucas is a full-out water playground for all ages, with wave runners, glass-bottom boats, and water taxis to Playa del Amor beneath El Arco. The surf can be unpredictable off both coasts, and swimming at solitary beaches isn't advisable.

Diehard anglers invest thousands in some of the world's most famous fishing tournaments in Los Cabos. They race to find the record-breaking marlin and sailfish, vying for million-dollar payouts for measuring and releasing 50-pound thrashing, glistening billfish. Less ambitious anglers get almost as big a thrill from catching marlin, sailfish, dorado, wahoo, tuna, and other seasonal species during fishing trips with dozens of operators. Tournament winners Pisces Sportfishing and Picante Bluewater Sportfishing run daily sportfishing charters from the San Lucas Marina. The fishing is equally exciting in La Paz, Loreto, and Ensenada.

Burros would still be wandering the sandy streets of Cabo San Lucas if the government hadn't swooped in to create a master-planned resort region here in the 1970s. San Lucas, Baja's southernmost city, has gone from a small town with a major fishing cannery to a huge city sprawling from the Cabo San Lucas harbor east to the surfing beaches on the Pacific. It's an anything goes kind of place, with bountiful bars for everyone from fishermen to college freshmen. The area's most popular beach, Playa Médano, is lined with laid-back bars with tables in the sand. A few famous restaurants and sushi bars add a touch of class and pull in guests from the posh resorts in the Corridor, the 18-mile-long highway north to San José.

Four mountain ranges bisect the Baja California Peninsula north to south, ending with the Sierra de la Giganta towering over Los Cabos. The only way to experience it all is by driving the length of the peninsula, taking at least three days each way. Todd Clement, a winner of the legendary Baja 1000 race, leads off-road tours from Ensenada and Los Cabos and a week-long dusty, thrilling ride from San Diego to Los Cabos with Wide Open Baja. Hiking, mountain biking, and Jeep tours to canyons, waterfalls, and natural springs near Los Cabos are available with Baja Wild.

Numerous prehistoric petroglyphs and murals can be found in caves in the Sierra de San Francisco near the early mission settlement of San Ignacio in central Baja. Access is limited to this UNESCO World Heritage Site with more than 400 murals; the easiest way to tour the site is with local guides from San Ignacio's Ecoturismo Kuyima. Cave painting tours are also available in Loreto and Mulege.

The Sonoran Desert claims more than 60 percent of Baja's landmass on both sides of the mountains. Mexico's largest protected area covers much of central Baja in the Vizcaíno Biosphere Preserve, including 280 miles of coastline, three gray whale sanctuaries, and a collection of petroglyphs in the mountains. Guerrero Negro, on the line between the two states, is the base for hiking, cave painting, and whale watching tours with local guides from Malarrimo Eco-Tours.

At 10,154 feet, Picacho del Diablo in the northern Sierra de San Pedro Mártir is Baja's highest peak. Part of a 170,000-acre national park, the mountains are home to a National Astronomy Observatory and several endangered condors released by scientists from the San Diego Zoo. Visited by only a few hundred hardy explorers each year, the park is reached via a 50-mile-long unpaved road off the Transpeninsular Highway south of Ensenada. Come here if you're ready to rough it. The only lodge in the region has closed, so your only option is camping out. If you'd prefer to do a day trip, Ecobaja Tours in Tijuana runs trips to the park.

Ever since Jack Nicklaus designed his first Palmilla course in Los Cabos in 1992, golf has grown to surpass fishing as the number-one sporting challenge in southern Baja. Sprinklers spray reclaimed water on unnatural greens at more than a dozen courses around Los Cabos, many charging Pebble Beach-level green fees. La Paz and Loreto have also become golf destinations, and several courses lure duffers across the border in northern Baja. The 27-hole Palmilla Golf Club (www.oneandonlypalmilla.com) was Jack Nicklaus' first Latin America design and set the standard for Los Cabos courses when it opened in 1993. Cabo del Sol's (www.cabodelsol.com/content/golf.html) two courses designed by Nicklaus and Tom Weiskopf rank at the top of Mexico's golf courses.

For info on Baja's many courses checkout www.bajagolf.com.

Missionaries began growing grapes in the Guadalupe Valley east of Ensenada in the late 1880s; modern wineries began drawing attention in the 1980s, and the valley is now rapidly evolving into a south-of-the-border Napa. More than two-dozen boutique and brand-name wineries are producing vintages worthy of international attention (Casa de Piedra and Monte Xanic show up on menus around the world), and a wine route is gradually evolving. Both a winery and a six-room inn, Adobe Guadalupe has been at the forefront of the valley's emergence since 1998 and a few other small inns have opened. But the valley is still an out-of-the-way place, about an hour's drive from Ensenada or three hours south of San Diego. Baja California Tours runs winery trips from San Diego. But most travelers typically make their way here from Ensenada and explore on their own. There's a good map of the wineries at www.wineriesinbaja.com.

For more info see www.discoverbajacalifornia.com/wine_country.

Kayakers set off on day and weeklong trips into the Sea of Cortez from Loreto and La Paz and are rewarded with year-round abundant whale, sea lion, and frigate sightings around cactus-spiked islands. On the Pacific Coast in Bahías Magdalena and San Ignacio, newborn whales float beside their mothers as kayakers paddle about during the winter. Baja Expeditions and Nichols Expeditions run seasonal trips.

Baja California Sur's capital city has a mainland Mexico feel, though new golf courses and marina developments are gradually gringo-izing its character. The city's seaside promenade on the Sea of Cortez's largest bay faces spectacular sunsets that bring out young couples, watchful grandmothers, and toddlers playing in the sand. Wandering around the Museo de Antropología, main plaza, and narrow streets lined with taco stands and shoe shops give you a real taste of Mexico. Cactus gardens, dusty pickups, and glimpses of the stark brown mountains are constant reminders of Baja's desert nature. The nearby Todos Santos islands lure kayakers and divers with their diverse wildlife; it's east to see why Jacques Cousteau called the Sea of Cortez "a marine aquarium." Cruise ships stop in on their way north to Loreto or south to Los Cabos; small luxury and adventure ships sail to isolated beaches and whale-watching grounds off Baja's shores.

Tijuana, Rosarito Beach, Ensenada, and San Felipe are the big draws in northern Baja near the U.S. border. Heavily influenced by California, they're classic border areas with curious tourists, carousing kids, endlessly tacky souvenirs, and restaurants good enough to draw diners across la frontera. The first three towns are easily reached on day trips from San Diego, while San Felipe is on the Sea of Cortez coast south of Mexicali, the capital of Baja California.

The Sea of Cortez offers divers the chance to swim with whale sharks, manta rays, sea lions, sea turtles, and hammerhead sharks around the seamounts and islands off La Paz. Baja Expeditions runs live aboard dive trips around the sea from June to November and day dive trips from La Paz. The region's only coral reef system grows close to shore around Cabo Pulmo. Snorkelers and divers spot seahorses and sea bass in 80-degree water during the summer and find small hotels, restaurants, dive shops, and campgrounds in a relatively unpopulated beachfront community. Divers make quick boat trips with Amigos del Mar to El Arco in Los Cabos to watch sandfalls spilling hundreds of feet down an undersea canyon.

California surfers camp and surf non-stop at puntas (points) around Rosarito Beach and Ensenada. Stars on the international surf circuit race to the Islas de Todos Santos near Ensenada for 10-foot swells during tropical storms and hang out with newbees at Costa Azul in San José del Cabo. Both coasts in the south have remote surf beaches like Punta Pescadero on the Sea of Cortez that are worth the rough four-wheel-drive approaches. Zippers restaurant at Costa Azul (Carretera Transpeninsular, Km. 28.5; 52-624-172-6162) is the unofficial headquarters for the Los Cabos surfing scene. The Mike Doyle Surf School at the Cabo Surf Hotel (52-624-142-2666; cabosurfshop.com/surfschool.htm) runs private and group surf classes and has board rentals.

Artists from Santa Fe, San Francisco, and Switzerland revel in the diffused light, churning surf, and subdued ambiance in this 19th century town an hour north of Los Cabos. At midday its historic center is often packed with sightseers browsing through nearly 20 art galleries and a scattering of jewelry, folk art, and décor shops. Locals emerge at dawn and dusk, gossiping over coffee, dropping by the post office, and dining on fresh seafood and homemade pasta. Nights are peaceful in this Pueblo Mágico, a designation the government gives well-preserved communities.

More than 20 species of whales frequent Baja's sea through the year. But the big whale show runs from January to March, when thousands of pregnant grey whales migrate to protected lagoons off Baja's southern Pacific shores to give birth. Hundreds of humans eager to come eyeball-to-eyeball with a baby leviathan quickly follow, setting up camp or staying in small basic hotels near San Ignacio Lagoon and Magdalena Bay on Baja's Pacific coast. Baja Expeditions and Baja Discovery run charter flights from San Diego to San Ignacio and have camps close to whale-watching sites. Aero Calafia offers flights from Los Cabos to the lagoons.