Arecibo gained more recent recognition for the astronomical contributions of the Arecibo Observatory. Once the largest single-aperture telescope in the world, it was surpassed in 2016 after more than 50 years. Hurricane Maria in 2017 and subsequent earthquakes damaged the site. The telescope's receiver platform and dome collapsed into the reflector dish on Dec. 1, 2020 — less than a month after the U.S. National Science Foundation announced decommissioning plans.
Cambalache State Forest (Bosque Estatal de Cambalache), midway between Arecibo and Barceloneta on Highway 22, is noted for its eucalyptus, teak, and mahoe trees. The forest is a popular destination for hiking and mountain biking; a permit is required for camping.