Cayo Acuario, Coral cay in San Andres archipelago, Colombia.

Cayo Acuario, also called Rose Cay, is a small coral cay east of San Andrés Island in the San Andrés and Providencia department. Its main feature is the shallow site known as "El Acuario", where large numbers of fish gather. The cay lies close to its sibling Haynes Cay and is a usual stop on the boat route to Johnny Cay.

The sources document no settlement history, fishing trade or inter-island exchange for this cay. They record only its position at 12°33′ N, 81°41′ W, east of San Andrés in the Department of San Andrés and Providencia, and its alternate name Rose Cay. Its documented role is as a stop on the boat route to Johnny Cay, beside Haynes Cay.

The cay's name comes from the fish life around it: the spot called "El Acuario" is where boats stop so visitors can snorkel among schools of fish. It lies just off Haynes Cay, and boats heading to Johnny Cay usually pass by. The cay has no town or residents; it is used as a daytime stop.

You can reach this place by boat from Spratt Bight Beach on San Andres Island, and the trip takes about 10 minutes each way. The shallow waters here mean conditions can change with the tides, so checking water conditions before you go helps with planning your visit.

What makes this place special is the natural walkway created by shallow water between Cayo Acuario and nearby Haynes Cay, letting people cross between both islands on foot when the tide is low. This connection shifts and changes with the water levels, giving visitors a different experience each time they come.