"Mona Island" redirects here. Mona is also an ancient or poetic name for the island of Anglesey or the Isle of Man.

Mona (Spanish:Isla de la Mona) is the third-largest island of the Puerto Rican archipelago, after the main island of Puerto Rico and Vieques. It is the largest of three islands located in the Mona Passage, a strait between the Dominican Republic and Puerto Rico, the others being Monito Island and Desecheo Island. It measures about 11 km by 7 km (7 miles by 4 miles), and lies 66 km (41 mi) west of Puerto Rico, of which it is administratively a part. The original name given to the island by the Taíno Indians is Amona, which means "what is in the middle", referring to the journey between the islands of Puerto Rico and Hispaniola. It is one of two islands that make up the Isla de Mona e Islote Monito Barrio of Mayagüez, Puerto Rico.