Much of the island is karst landscape and it has a wealth of ancient and medieval sites including Dún Aonghasa, described as "the most magnificent barbaric monument in Europe" by George Petrie.

[7] Because the island is in the Gaeltacht, Árainn is the only legal placename in Irish or English as declared in the Official Languages Act 2003.

The terrain of the island is composed of limestone pavements with crisscrossing cracks known as "grikes", leaving isolated rocks called "clints".

Pre-existing lines of weakness in the rock (vertical joints) contribute to the formation of extensive fissures separated by clints (flat pavement like slabs).

[9] The grikes (crevices) provide moist shelter, thus supporting a wide range of plants including dwarf shrubs.

But when the limestone pavement is covered by a thin layer of soil, patches of grass are seen, interspersed with plants like the gentian and orchids.

Insects present include the butterfly the pearl-bordered fritillary (Boloria euphrosyne), brown hairstreak (Thecla betulae), marsh fritillary (Euphydryas aurinia) and wood white (Leptidea sinapis); the moths, the burren green (Calamia tridens), Irish annulet (Gnophos dumetata) and transparent burnet (Zygaena purpuralis); and the hoverfly Doros profuges.

Private minibuses, horse-drawn carriages and bicycles are the main methods of getting about for the numerous tourists who visit the island in the summer months.

Nearby are a Neolithic tomb and a small heritage park at Dún Eochla, featuring examples of a traditional thatched cottage and poteen distillery.

The island appeared on the premiere episode of The Amazing Race 12 with teams needing to find Teampall Bheanáin after they arrived.