• Rincón de la Vieja National Park (northeast of Liberia, in Guanacaste): This is an area of rugged beauty and high volcanic activity. The Rincón de la Vieja Volcano rises to 1,848m (6,061 ft.), but the thermal activity is spread out along its flanks, where numerous geysers, vents, and fumaroles let off its heat and steam. This is a great place to hire a guide and a horse for a day, with waterfalls and mud baths, hot springs, and cool jungle swimming holes to explore. You'll pass through pastureland, scrub savanna, and moist secondary forest; the bird-watching is excellent.
  • The Río Sarapiquí Region (north of San José btw. Guanacaste in the west and the Caribbean coast in the east): This region is a prime place for an ecolodge experience. Protected tropical forests climb from the Caribbean coastal lowlands up into the central mountains, affording you a glimpse of a plethora of life zones and ecosystems. Braulio Carrillo National Park borders several other private reserves here, and a variety of ecolodges will suit any budget.
  • Arenal Volcano/Tabacón Hot Springs (near La Fortuna, northwest of San José): When the skies are clear and the lava is flowing, Arenal Volcano offers a thrilling light show accompanied by an earthshaking rumble that defies description. You can even see the show while soaking in a natural hot spring and having a drink at the swim-up bar at Tabacón Grand Spa Thermal Resort. If the rushing torrent of volcano-heated spring water isn't therapeutic enough, you can get an expert massage here. 
  • Monteverde Cloud Forest Biological Reserve (in the mountains northwest of San José): There's something both eerie and majestic about walking around in the early morning mist surrounded by bird calls and towering trees hung heavy in broad bromeliads, flowering orchids, and hanging moss and vines. The reserve has a well-maintained network of trails, and the community is truly involved in conservation. Not only that, but in and around Monteverde and Santa Elena, you'll find a whole slew of related activities and attractions, including canopy tours that allow you to swing from treetop to treetop while hanging from a skinny cable.
  • Manuel Antonio (near Quepos on the central Pacific coast): Why is this place so popular? Monkeys! The national park here is full of them, even the endangered squirrel monkeys. But you'll also find plenty to see and do outside the park. The road into Manuel Antonio has many lookouts that consistently offer postcard-perfect snapshots of steep jungle hills meeting the sea. Uninhabited islands lie just off the coast, and the beaches here are perfect crescents of soft white sand.
  • Osa Peninsula (in southern Costa Rica): This is Costa Rica's most remote and biologically rich region. Corcovado National Park, the largest remaining patch of virgin lowland tropical rainforest in Central America, takes up much of the Osa Peninsula. Jaguars, crocodiles, and scarlet macaws all call this place home. Whether you stay in a luxury nature lodge in Drake Bay or outside of Puerto Jiménez, or camp in the park itself, you will be surrounded by some of the most lush and most intense jungle this country has to offer.
  • Tortuguero Village & Jungle Canals (on the Caribbean coast, north of Limón): Tortuguero Village is a small collection of rustic wooden shacks on a narrow spit of land between the Caribbean Sea and a dense maze of jungle canals. It's been called Costa Rica's Venice, but it actually has more in common with the South American Amazon. As you explore the narrow canals here, you'll see a wide variety of herons and other water birds, three types of monkeys, three-toed sloths, and caimans. If you come between June and October, you might be treated to the awe-inspiring spectacle of a green turtle nesting—the small stretch of Tortuguero beach is the last remaining major nesting site of this endangered animal.

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.