The islands lie close to the coast of the Mullet Peninsula but in their geological type, they are composed of quartzite rock like that found on Achill Island and not like that of the Mullet off which it lies, which is composed largely of schists, slate, gneiss and white psammite with a granite deposit at Termon Hill near its southern end.
Unlike its neighbouring islands of the Inishkeas and Inishglora, which are largely white sand and machair, blanket bog formed on Duvillaun.
Fulmars and kittiwakes nest on the cliffs, peregrine falcons hover, keeping a keen eye out for prey.
Duvillaun Mor, which lies only a kilometer or so off Falmore at the southern tip of the Mullet Peninsula, has monastic remains which most likely date from the Early Christian period - i.e. 6th to 8th century AD, similar to the archaeological remains on Inishkea South and on Inishglora.
There is a Gallerus-type oratory similar to that on Inishglora, a tomb with large stone slabs, one of which is inscribed with a depiction of the crucifixion.