The SW face of the atoll is formed by Mamanago Faro, at its SW extremity, and three similar lagoon reefs farther N.

Maregiri lies at the S end of the NW side of the atoll. From this islet the barrier reef, consisting of a series of lagoon reefs, some with small unnamed islets, extends about 25 miles NNE. These reefs lack above-water features and are therefore difficult to identify; the channels between them are therefore better avoided, especially since the central part of the lagoon is unsafe for navigation.

Moresby Channel, separating North Malosmadulu Atoll and South Malosmadulu Atoll, has depths over 183m and is free from known dangers. The W entrance to this channel has no wooded islet near it and is difficult to identify.

The Malosmadulu atoll includes goidhoo atoll.