Arecibo is a city and municipality on the northern coast of Puerto Rico, on the shores of the Atlantic Ocean, located north of Utuado and Ciales; east of Hatillo; and west of Barceloneta and Florida. It is about 50 miles west of San Juan, the capital city. Arecibo is the largest municipality in Puerto Rico by area, and is part of the San Juan, Caguas and Guaynabo Metropolitan Statistical Area. It is spread over 18 barrios and Arecibo Pueblo. Its population in 2020 was 87,754.
The Arecibo Observatory, which housed the Arecibo telescope, the world's largest radio telescope until July 2016, is located in the municipality. The Arecibo telescope collapsed on December 1, 2020. Arecibo is the seat of the Roman Catholic Diocese of Arecibo.