Concierge.com's insider take:
Costa Rica's northwest quarter is distinctive for its lingering dry season and deciduous forests that flare in spectacular blooms in spring before shedding their leaves—all the better for viewing wildlife. Inland, Guanacaste is cowboy country: Horseback rides are popular at towns near Rincón de la Vieja National Park and its namesake volcano. Three more volcanoes—Tenorio, Orosi, and Miravalles—stud the Guanacaste mountain range. Animal viewing is a key draw in the tropical dry forest of Santa Rosa National Park and in the wetlands of Palo Verde National Park, where you might come across such creatures as crocodiles, jabiru storks, and roseate spoonbills. Santa Rosa is best explored by hiking, although a high-ground-clearance vehicle is needed to reach the beaches. The tropical forests and wetlands of Palo Verde are readily accessible via guided boat trips from Hacienda El Viejo on the northern end of the Nicoya Peninsula—close enough for half-day trips from the major beach towns, such as Playas del Coco and Tamarindo.