If a 12-year-old had a life list, we bet the rainforest of Costa Rica’s Osa Peninsula would be near the top. With activities that range from tree climbing to rappelling down waterfalls, it’s a paradise full of new adventures—with a hammock at the end of the day.If a 12-year-old had a life listing, we guess the rainforest of Costa Rica’s Osa Peninsula would be close to the highest. With activities that vary from tree mountaineering to rappelling down waterfalls, it’s a paradise full of new adventures—with a hammock on the finish of the day.