Arenal Observatory Lodge
Built in 1987 as a Smithsonian Institute scientific research station, this sprawling complex was constructed atop a ridge just 2.7km (1.7mi) from the crater, supposedly safer than La Fortuna from the lava and ash eruptions that rocked the region throughout the 1980s and 90s. Today, Arenal is a quieter, though still technically active volcano, but still seems larger than life when viewed Arenal Observatory’s restaurant and hotel.
Even if the mountain is veiled in mists, there’s still plenty to explore on the Observatory’s enormous grounds. You can explore the 800 acres of primary and secondary rainforest, gardens, and farms on more than 11km (7mi) of trails, some of which connect to adjacent Arenal National Park. Sturdy hikers can begin at the observatory and traverse the park, via Cerro Chato, and arrive at La Fortuna Waterfall before sundown.
The Observatory also offers several guided treks, including special tours for birders, and many other activities and amenities.