Ilheu de Santa Maria is the low, rocky islet just off Praia's harbourfront, facing Gamboa and the city centre. It is small, uninhabited, and easy to overlook, but it has carried more history than its size suggests: old customs buildings, quarantine use, and repeated plans to turn it into a resort or casino.
For most travellers it is a view rather than a full excursion. Look for it from the waterfront, especially late in the day when the harbour light catches the ruins and the plateau behind Praia rises in the background.