Costa Rica Guide
The Zona Norte
Parque Nacional Volcán Arenal
Volcán Arenal was afforded protected status in 1995, becoming part of the national parks system as the Parque Nacional Volcán Arenal (daily 8am–4pm; $6; 
461-8499). Though Volcán Arenal is one of the most active volcanoes in the Americas, whether you see any lava flow depends very much on the weather. In the rainy season the spectacular night flows are very elusive, hidden by shrouds of mist and cloud. If you can't see the summit, the park's visitor centre has video displays of the volcano's more spectacular activity and if nothing else, you'll certainly hear unearthly rumbling and sporadically feel the ground shake, especially at night.
The park contains a handful of good trails, some of them across lava fields; the four-kilometre Tucanes Trail takes you to the part of the forest that was flattened by an eruption in 1968. On these hikes, you may see some wildlife; birds (including oropéndolas and tanagers) and agoutis are particularly common. Although the park has a simple café, it's best to take a picnic lunch and plenty of water if you intend to walk extensively. Hiking any distance up the volcano's sides has always been energetically discouraged, and fences now stop you from doing so.
The park can only be visited after dark on one of the night tours leaving La Fortuna every afternoon at about 3–4pm. Most operators run them even when it's cloudy, in the hope that the clouds will lift or the opposite side of the volcano will be clear. None offers you a refund if you don't see anything, so you might want to wait for a clear evening before signing up. Aventuras Arenal run a sunset boat tour on which you can watch the action from Laguna de Arenal.
The park entrance is 14km west of La Fortuna; look for the well-signed driveway off to the left. If without a vehicle, taxis head from La Fortuna to the west side of the volcano for around $35 round-trip per car, including waiting time of a few hours. Unless you're in a large group, it's cheaper – and less bother – to take a tour. The cheaper public bus from La Fortuna drops passengers off 2km from the park entrance, though the return journey can be tricky – unless you manage to connect with the bus coming from Tilarán or Arenal Town, you could try to get a ride back with other park visitors. Hitching on the main road is quite easy. A better option is the free bus run by Rancho Margot in El Castillo which leaves four times daily from outside the church in La Fortuna and passes the national park entrance on its way to the ranch; the driver will let you off on request. You can flag down the bus when it makes its return journeys from El Castillo to La Fortuna.