Isla de Cabras is an islet located at the entrance of San Juan Bay, immediately across from San Juan Islet in Puerto Rico. It is part of the Palo Seco barrio of the municipality of Toa Baja. The island is home to El Cañuelo fort, which alongside El Morro castle on San Juan Islet, protected San Juan Bay, the harbor of the historic city of Old San Juan, from competing world powers during the Age of Sail.