Following convenient pickup around 8am at your San Juan accommodation, board a comfortable tour vehicle headed west for a Puerto Rican town.
Back in your tour vehicle, head for the town of Arecibo, where you'll visit the Arecibo Observatory. Take a guided tour of the biggest radio telescope on earth and view a documentary about the telescope and its construction. Departing the observatory, stop for a traditional Puerto Rican lunch at a local spot (own expense).
Visit Cueva del Indio, a sea cave decorated with petroglyphs crated by the island's original inhabitants, the Taino Indians. Then visit a black magnetic sand beach to relax, walk in the ocean, and snap photos of this natural phenomenon.
Return to your San Juan accommodation for drop-off at the end of your tour.