Most of the volcanoes in Costa Rica lie in the northern part of the country and Central Highlands. They played an important role in how the lush landscape of this region came into existence. Due to many eruptions, the soil here is fertile and rich with various minerals. That fertility has contributed to verdant forests thick with tropical and exotic vegetation that supports a myriad of bird and wildlife species.

Trails, explored independently or with a guide, leading up to all the volcanoes are attractions within themselves, displaying the huge variety of unusual flora and fauna.

Because it spews hot gases and steam on a regular basis, Arenal in Arenal Volcano National Park (506-2461-8499) is the favorite for most visitors. In fact, of the 2 million tourists that pass through Costa Rica each year, about 1.25 million come to this site. Since it’s often shrouded by cloud cover, many travelers visit at night.

But there are other reasons for choosing the area. Arenal is the most visited because it’s the one volcano with the widest range of activities and its location is close to airports and beaches.

What else is there to do in Arenal? Many visitors take in the 15 Arenal Hanging Bridges, which form a trail that has been a tourist attraction since 2003. The colors alone are dazzling, from emerald green leaves to cherry-red berries and flowers. On a two-mile trek across steps and bridges, visitors are also likely to see such animals as howler monkeys, whose call can be as loud as a lion’s roar.

The most easily accessible active volcano is Poas in Poas National Park (506-2482-2165). It has only one active crater, with a boiling acid lake, while one of the inactive craters has a lovely icy lake. The best time to go is May to November, when clear weather allows visitors to take in the volcano’s active crater. Be aware that Poas can get crowded and cloudy, so arrive early in the day when views are better, and there are fewer visitors.

The 100-square-mile Cano Negro National Wildlife Refuge (506-2681-9464) is known for its fishing and bird-watching experiences.

Venado Caverns (506-2384-9616 web site? ). This subterranean network of limestone caves, streams and tunnels formed more than 7 million years ago. Excursions require gear boots and flashlights.