The town of La Fortuna is the main gateway to Volcán Arenal , which looms to the southwest.
A decade ago, La Fortuna was a dusty little agricultural town with potholed dirt streets. Today it thrives on tourist traffic.
West from La Fortuna, the road begins a gradual, winding ascent to Lake Arenal  around the northern flank of Arenal Volcano, 15 kilometers from town. It’s a stupendously scenic drive.
In town there’s not much to see except the church on the west side of the landscaped plaza, anchored by a sculpture of a volcano, but outside town the range of activities is the most concentrated in the nation, with enough to occupy visitors for a week; Arenal Waterfall Gardens  and the nearby thermal springs and spas  are not to be missed!
Other nearby sights include…
This preserve (tel. 506/2479-7019, www.ecocentrodanaus.com , 8 a.m.–4 p.m. daily, $5 admission with tour), three kilometers east of town, has trails through a netted butterfly garden. A separate garden features red-eyed tree frogs and poison-dart frogs in re-creations of their natural environments; there are also eyelash vipers in cages. A small lake has caimans, turtles, and waterfowl. The 6 p.m. night walk (by reservation) is recommended.
This ecological tropical park (tel. 506/2479-9762, www.arenalmundoaventura.com , 8 a.m.–5 p.m. daily), two kilometers south of La Fortuna on the Chachagua  road, is a 552-hectare rainforest reserve that offers waterfall rappelling ($65), zip-line tours ($65), horseback rides ($40), and nature trails with guided hikes ($35), including a nocturnal walk. Frog and snake ponds, plus thermal swimming pools, are planned. Malekú indians demonstrate traditional music and dance in a traditional indigenous village.
La Fortuna Waterfall Ecological Reserve (tel. 506/2479-8078, www.arenaladifort.com , 8 a.m.–5 p.m. daily, closed during heavy rains, $7 or $10 with guide), about four kilometers south of town, is in the care of a local community development group—the Asociación de Desarrollo Integral de La Fortuna. The turnoff for the falls is two kilometers southeast of town, where a paved road leads uphill 2.5 kilometers to the entrance.
You can view the falls in the distance from a mirador (lookout), where a slippery and precipitous trail (20 minutes’ walk) leads down a steep ravine to the base of the cascade; there are steps and handrails for the steepest sections. Swimming is not advised. The Americas Paradise Center (tel. 506/2479-7777), adjoining, offers guided two-hour hikes up Cerro Chato volcano from here ($10 pp).
Initiated in 2010, Arenal Natura (tel. 506/2479-1616, www.arenalnatura.com , 8 a.m.–7:30 p.m. daily, $35 adults, $17.50 children), six kilometers west of La Fortuna, offers superbly executed exhibits on frogs, snakes, butterflies, and crocodiles. The ranarium displays more than 30 frog species plus an equal number of snake species (from eyelash vipers to the dreaded fer-de-lance) in large glass cages with excellent English-language signage. Crocodiles can be viewed sloshing about in a lagoon. Night tours are offered by reservation and well-versed guides lead tours.
Six kilometers west of La Fortuna, this resort (tel. 506/2479-1000, www.hotelloslagos.com , $10) has a quasi-theme park with 400 hectares of primary forest with trails and horseback riding, plus a ranarium (frog exhibit), butterfly garden, leaf-cutter-ant showcase, and lush gardens with water slides augering down to hot- and cold-water swimming pools. It also hosts the Canopy Tour Los Cañones.
Autotransportes San Carlos (tel. 506/2255-0567) buses depart San José  from Calle 12, Avenidas 7/9, at 6:15 a.m., 8:40 a.m., and 11:30 a.m. daily ($3). Return buses depart La Fortuna from the south side of the plaza at 12:45 p.m. and 2:45 p.m. Buses (tel. 506/2460-3480) depart Ciudad Quesada  for La Fortuna 13 times daily (irregular hours, $1.05).
Interbus (tel. 506/2283-5573, www.interbusonline.com ) and Grayline Costa Rica (tel. 506/2220-2126, www.graylinecostarica.com ) operate shuttles from San José ($35) and popular tourist destinations in Nicoya  and Guanacaste .
Alamo (tel. 506/2479-9090, www.alamocostarica.com ) has a car rental office in town. Bike Rental Arenal (tel. 506/2479-7150, www.bikearenal.com ) rents mountain bikes ($22 daily, $132 weekly). Segway Costa Rica (tel. 506/2479-8736, www.segwaycostarica.com , $39 age 8 and older) offers tours of the town by Segway glider at 9 a.m., 1 p.m., and 4 p.m.