Bounded by jungle-draped volcanoes and the turquoise Pacific Ocean, Costa Rica’s Guanacaste province offers a tropical safari full of treasures. On the outer edge of the Nicoya Peninsula, head to the wild beach at night in search of one of nature’s most wondrous phenomena, the arribada (Spanish for “arrival”), a mass nesting event when thousands of olive ridley sea turtles come ashore to lay their eggs. With luck, we may see hundreds of tiny hatchlings scurry to the sea. Inland, explore private rainforest reserves home to sloths, howler monkeys, rare parrots and more endangered tapirs than anywhere else in Costa Rica. This charming mammal—related to horses and rhinos, even though it looks more like an elephant or a pig—is highly elusive, but our odds to spy them here are high.