2 Best Sights in Sonora, Mexico

The somewhat difficult trip to El Pinacate is also one of the region's most rewarding. The reserve, midway between Puerto Peñasco and the Arizona border, is famous for volcanic rock formations and thousands of moonlike craters. Highlights include 4,000-foot-high Santa Clara peak, and the mile-wide El Elegante crater, created by a giant steam eruption 150,000 years ago.

With the addition of a solar-powered visitor center, which opened in 2009, exploring the area isn't quite as daunting. But you'll still need to plan ahead, bringing your own water, food, and extra gasoline. A high-clearance four-wheel-drive vehicle is also strongly advised. Since an unpopulated stretch of desert is a great place for drug trafficking and illegal border crossings, use common sense. Lastly, be mindful of the heat—summer temperatures can be blistering. The best time to visit is between November and March.

All visitors must register at the park entrance, where a ranger's station provides informative tips for visitors. For current park information, contact the International Sonoran Desert Alliance in Ajo, Arizona, at 520/387–6823 in U.S. Hwy. 8, Km 51, Esperanza, near Ejido Nayarit, Puerto Peñasco, Sonora, 83550. 638/384–9007. $3. Daily 9–5.

Excellent naturalist-led tours can also be arranged through La Ruta de Sonora in Tucson. 520/886–6555 in U.S. www.laruta.org.

The northern Gulf area forms an impressive desert-coast ecosystem, and scientists conduct research programs at the Intercultural Center for the Study of Desert and Oceans (known as CEDO, its acronym in Spanish), about 3 km (2 mi) east of town on Fremont Boulevard in the Fraccionamiento Las Conchas neighborhood. You can take an English-language tour of the facility to learn about the ecology of the area and its history, or just pick up a tide calendar (useful if you're planning beach activities) or field guide from the gift shop. Talks and nature outings—including tide-pool walks, Pinacate volcano excursions, and kayaking expeditions of area estuaries—are on offer.