The boom in tourism has given birth to dozens of tour operators that line the streets of San Pedro, which can be classified into two divisions: traditional tours and active expeditions (although a few offer both). Always try to book a reservation ahead of time, especially during the summer. Tour operators have minimum group sizes, but if you've made a reservation, they will take you regardless of the group size being under the minimum.

If you can afford it, I strongly recommend hiring a private guide. A private guide will take you on uncommon tours, such as the remote salt flat Salar de Tara, and can adapt to your whims. Many are ex-guides from luxury hotels, with years of experience and insider contacts around town, but turnover is high, so check with Sernatur to contact a registered guide. The professional outfitter Azimut 360 (tel. 2/235-1519; www.azimut.cl), based in Santiago, offers weeklong customized adventure trips throughout Chile and Argentina and classic day trips around San Pedro which extend to the far reaches of the desert north. It can guide climbers up one of the four volcano routes in Chile and Bolivia. Costs vary; normally, a private guide charges one fee, around $60 to $80 (£40-£53) per day for two to four people, and $100 (£67) for six. Extras, including lunch, a car and driver, and entrance fees, can push the daily cost up to around $230 (£153) for a group of two to four people.

For traditional tours (Valle de la Luna, the Salar de Atacama, Tatio Geysers, and archaeological tours), the following are tried and true: Desert Adventure, corner of Tocopilla and Caracoles (tel./fax 55/851067; www.desertadventure.cl); TurisTour (tel. 55/851380); Cosmo Andino Expediciones, Caracoles s/n (tel. 55/851069); or Atacama Connection, Caracoles and Toconao (tel./fax 55/851421; www.atacamaconnection.com). For traditional tours with a wildlife theme, try Natura Expeditions, Domingo Atienza 388 (tel. 55/851825). For mountain biking and sandboarding, try Southamericanadventure, Caracoles 317 (tel. 55/851373). Average prices are: Valle de la Luna, $11 (£7.30); Tatio Geysers, $27 (£18); salt flat and altiplanic lakes, $44 (£29).

Marvel at the clear night skies with Space, Caracoles 166 (tel. 55/851935; www.spaceobs.com), which gives amateur astronomers an opportunity to view constellations visible only in the Southern Hemisphere. Space has the largest diameter telescope (60cm) available for public use in South America. Two even larger telescopes currently under construction will be available to the public at the end of 2009. The 3-hour tour leaves nightly except for evenings around a full moon, and costs $19 (£13), which includes transportation, use of the powerful telescopes, and an easy-to-understand interpretation of the stars. Tours in English are not always available so try to reserve a couple of days in advance.

In Town -- San Pedro is chock-full of handicraft boutiques, and there is a crafts fair that begins at the plaza, between the Municipal Building and the museum. Many of the hotels and restaurants also feature art and sculpture exhibitions influenced by the Atacama Culture, notably Hotel Kimal and Adobe restaurant.

National Flamingo Reserve: The Salar de Atacama, Valle de La Luna & the Southern Altiplanic Lakes

The National Flamingo Reserve is divided into seven sectors and distributed over a vast area of land, including portions of the Salar de Atacama (Atacama Salt Flat). A trip to the Salar is among San Pedro's most accessible destinations (as is Valle de la Luna). The Salar is a tremendous 100km-long (62-mile) mineralized lake with no outlet, and it is covered nearly completely by saline minerals and dust that combine to create a weird putty-colored crust. The salt crystals are formed by the evaporation of saline water that is unable to escape from the basin. The salt flat is the largest in Chile, and it is home to 40% of the world's lithium reserves. In some areas, lagoons peek out from under the crust, such as at Laguna Chaxa, the traditional stop at the Salar due to the Conaf interpretative center here; the center is open daily September to May 8:30am to 8pm and June to August 8:30am to 7pm and there's a $3/£2 park entry fee. But it is difficult to see flamingos at Chaxa, and as destinations go, it is a fairly boring stop. Most tour companies also run daily excursions to Laguna Sejar, some 19km (12 miles) from San Pedro. This emerald lagoon affords a remarkable swimming experience; swimmers float in water so saline -- Sejar contains even greater levels of salt and lithium than the Dead Sea -- that it renders them virtually unsinkable. Shards of protruding, jagged salt crests can prove lethal; flip flops or sandals are essential. Bring a couple of large bottles of fresh water to rinse yourself off with afterward. Renting a bike to come here is an option but be aware that some parts of the road are very sandy and can be a little tricky to navigate, so ask someone at your hotel to explain the route to you carefully. It's best to visit early in the day, when there is no wind.

Valle de la Luna (Valley of the Moon) with its ethereal lunar landscape, mountains streaked with pink, and foreboding silence, is the poster child of the Atacama Desert. The valley is a depression surrounded by jagged spines of salt-encrusted hills, with an immense sand dune running between two ridges. Most tours include a 15-minute (tours depart at 3 or 4:30pm, depending on the season) stroll through the Cordillera de Sal (Salt Hill Range), where you will literally hear the rocks cracking, before ending at a lookout point reached by a 15-minute, fairly steep ascent along a sandy pathway at sunset. This is the best site to enjoy Atacama Desert's colors as they melt from violet to gold. You'll share this lookout point during the sunset hour with a hundred or more tourists, especially during the summer. For an unforgettable night, come on the eve of a full moon, when ghostly light casts shadows on an already eerie landscape. The Valle is 15km (9 1/4 miles) from San Pedro and can be reached by bicycle or vehicle. To get here, head west on the street Licancabúr toward Calama, and follow the left-turn sign for Valle de la Luna. Tour prices do not include admission to the national park, which costs $4.50 (£3). Warning: There's a minefield between the northern park gate and the main highway to Calama. Heed the warning signs, and don't wander off around the gate.

Heading south 38km (24 miles) from San Pedro, you will reach the oasis towns of Toconao, Camar, and Socaire. These three towns are not as picturesque as their counterparts in the Atacama Desert, so you might want to just continue on. What you should head for are the high altiplanic lakes, Laguna Miscanti and Laguna Miñeques, two stunning cobalt-blue lakes at the foot of their respectively named peaks, and the Salar de Talar and the Laguna de Tuyajto, where it is easier to spot flamingos than at the Salar de Atacama. This journey is recommended in order to view high-altitude lakes on a less strenuous trip than the Salar de Tara, near the Argentina/Bolivia/Chile border. More adventurous types are better off visiting Tara because the reserve is larger, the salt flat's colors are more intense, and there are no other tourists. The Salar de Tara (also part of the Flamingo Reserve) rates as one of the most memorable journeys in the Atacama area, but few visitors are aware of it. The trip requires a round-trip 200km (124-mile) drive mostly along bumpy roads in a 4*4, along with a moderate hike.

Geysers del Tatio/Baños de Puritama

Without a doubt a highlight in the Atacama Desert, the Geysers del Tatio (Tatio Geysers) are nonetheless not the easiest excursion -- there's not a lot of physical activity required, but tours leave at 4 or 5am (the geysers are most active around 6-8am). At 4,321m (14,173 ft.), these are the highest geysers in the world, and it is a marvelous spectacle to watch thick plumes of steam blow from holes in such a windswept, arid land. Interspersed between the geysers, bubbling pools encrusted with colorful minerals splash and splutter -- but exercise extreme caution when walking near the thin crust; careless visitors burn themselves here frequently. Herds of vicuñas, the smallest camelid, with the animal kingdom's finest wool, graze in this area. There is a hot springs pool at the geyser site that most tours stop at, but I urge you to find a tour company that includes Baños de Puritama. A lump of rusting metal at the geysers is what's left of a previous misguided attempt to industrialize the underground source of energy. The geysers are 95km (59 miles) north of San Pedro. I strongly recommend travelers with their own vehicle not drive here -- even habitual drivers to the geysers can get lost in the dark amid myriad dirt roads. If you insist, buy a map at the military's geographic institute in Santiago and get an experienced driver to run you through details of the route, or hire a day guide. The Turistel maps are good in general but often lack sufficient detail when you really need it at the dirt-road level.

Due to the high altitude, this journey is not recommended on the first or second day of your stay in San Pedro. Some travelers save this for last, returning directly to Calama with stops at colonial villages and ruin sites. But it is a long journey, and a far better option is to head back to San Pedro and stop at the Baños de Puritama, a sybaritic hot springs oasis composed of well-built rock pools that descend down a gorge, about 60km (37 miles) from the geysers (or 28km/17 miles from San Pedro, heading out on the road that borders the cemetery). They are run by the luxury Hotel explora and cost a steep $16 (£11) to enter, but it's worth it. You may want to tote a snack and a bottle of wine to enjoy while there. There are changing rooms and bathrooms on the premises.

Pukara de Quitor

The Pukará is a 12th-century, pre-Inca fort that clings to a steep hillside some 3km (1 3/4 miles) outside San Pedro. Although formidable, the fort was no match for the Spanish, with their horses and steel swords, and it was conquered in 1540 by Francisco de Aguirre and 30 other men. Beyond its strategic purpose, the fort was also inhabited and many of the unmarked terraced enclosures -- which number over 200 -- would have been living spaces, patios, and kitchens. It requires a healthy imagination to visualize the site as a powerful defensive fortification, but there is a palpable energy about the place that invites soulful contemplation. It takes a further 15 minutes (a moderate climb) to reach the top of the fort. This is an ideal bike ride from San Pedro but a searing hot walk during the middle of the day.

There are information boards in English and a small information office with facilities. Entrance to the site is $3 (£2). On bike, you may want to continue north from the Pukará up through the valley along the dirt road for 2km (1 1/4 miles), where a short scramble up the eastern, right-hand ridge will take you to the tiny Inca ruin of Catarpe. It's a quiet, pensive spot with a beautiful view of Licancabur and other Andean peaks.

Aldea de Tulor

Tulor, Atacama's oldest pueblo, is a fascinating attraction, if only because of its age, estimated to have been built around 800 B.C. The site remained intact in part because it had been covered with sand for hundreds of years, and today it is possible to see the walls that once formed the structures of this town. There are a few reconstructed houses on view as well. Tulor is 9km (5 1/2 miles) southwest of San Pedro.

Bolivia's Laguna Verde

Why not visit Bolivia for the day? Early afternoon journeys to the shimmering turquoise lakes on the backside of Volcano Lincancabur put travelers in a high-altitude wonderland including a hot springs pool. This is an easy journey, but perhaps not as grand as the Salar de Tara. Rental vehicles may not cross the border; if you have your own vehicle, you'll need to register at Customs on the road out to Bolivia and pay an entrance fee at the Bolivian border. Better still, go with a Bolivian tour operator out of San Pedro. Try Colque Tours, at the corner of Caracoles and Calama (tel. 55/851109; www.colquetours.com). They can also take you deeper into Bolivia to the fantastic, snow-white salt flats of Uyuni, the biggest in the world.

Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.