Get up bright and early to visit Arenal Volcano National Park, which surrounds the towering Arenal Volcano. This park is known for its hiking trails and abundant plant and wildlife, with hundreds of bird species, tropical flowers, and plants. Depending on how much time you spend hiking in the park, you may also want to add a trip to the nearby La Fortuna Waterfalls to your morning. Don't forget to pack a swimsuit: The 200-foot-high (61-meter-high) waterfall drops into crystalline waters; pools farthest from the waterfall are generally calm and safe for swimming.

With all the volcanic activity around La Fortuna, it's no surprise that the area is full of hot springs, and going for a soak is a great way to relax after a morning of hiking. Many hotels have their own thermal pools, but you don't need to be a guest at a hot-springs resort to take advantage of healing waters; many offer half- or full-day passes, and some area tours include hot spring stopovers. The popular Tabacon Hot Springs offer a variety of features, from a thermal water slide to a swim-up bar. For something more family-friendly, Kalambu Hot Springs Water Park offers play areas and a 4-story rafting waterslide.

In the evening, head out to Mistico Arenal Hanging Bridges Park to explore the rain forest by night on a guided hike. The park has 16 hanging bridges that span around 1.6 miles (2.6 kilometers), traversing the top of the rain forest canopy. While it's a popular daytime spot, especially for photographers and bird-watching enthusiasts, visiting by night gives you the opportunity to view and learn about the park’s nocturnal creatures when they are at their most active.