Four days gives a solid introduction to La Fortuna and the Arenal Volcano area, balancing active days with the hot springs that make this one of Costa Rica's most relaxing destinations alongside its adventure-tourism reputation. Day 1 is for arrival and easing in. Settle into your accommodation, then head to a natural hot spring as the sun sets behind the volcano — whether you choose a free riverside spot or a resort-style complex, this is the right introduction to the area and a good way to recover from travel before more active days follow. Day 2 covers Arenal Volcano National Park itself. Hike the old lava trails for close-up views of the volcano's slopes, keeping an eye out for sloths, toucans, and coatis along the way — a knowledgeable guide significantly improves your odds of actually spotting wildlife that's otherwise easy to miss. The hike is moderate rather than strenuous, making it accessible to most fitness levels. Day 3 combines adventure and a different kind of nature experience. Canopy zip-lining through the rainforest is the area's signature adrenaline activity, and pairing it with the Mistico Hanging Bridges in the same day gives a calmer wildlife-spotting alternative at treetop level if you want to slow the pace by afternoon. Both activities are widely available through operators based in La Fortuna town. Day 4, if you have it, is best spent as a flexible day — return to a different hot spring than your first night's choice, or use the time for a less-rushed wildlife walk with a focus on photography rather than covering ground. La Fortuna rewards this kind of unstructured time as much as its scheduled activities. A few practical notes: book a guide for wildlife spotting specifically — sloths, toucans, and snakes are far easier to find with someone trained to look for them than on your own. Pack for both sun and rain regardless of season, since weather shifts quickly even in the dry months. And try at least one free public hot spring alongside any paid resort access, as the Río Tabacón area has both options within a short distance of each other.