Curaçao's most majestic natural wonder is a hidden cave on its western shore, accessible only via the ocean. The prime attraction of the cave is its electric-blue color, created by sunlight refracting off the water's surface, and the hauntingly beautiful scene inside includes small schools of fish and the occasional lobster. Entering and exiting the cave can be a bit tricky, so it's best to book a boat or snorkel tour with a recommended operator.
More adventurous types can boat or kayak from a nearby water-sports shop, or hike to the spot and then plunge into the water from the top of the cave (ask for exact directions from a local). When the tide is low, it's possible to enter the cave without going underwater. As the tide rises, the only way to enter is to free dive, which can be frightening. Also note that those who hike and jump need considerable arm strength to climb back up the rocks.