Inishmaan (/ˌɪnɪʃˈmæn/ IN-ish-MAN; Irish: Inis Meáin [ˈɪnʲɪʃ mʲaːnʲ], the official name, formerly spelled Inis Meadhóin, meaning "middle island") is the middle of the three main Aran Islands in Galway Bay, off the west coast of Ireland.

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

The limestones date from the Visean period (Lower Carboniferous), formed as sediments in a tropical sea about 350 million years ago, and compressed into horizontal strata with fossil corals, crinoids, sea urchins, and ammonites.

The effects of the last glacial period (the Midlandian) are most in evidence, with the island overrun by ice during this glaciation.

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

The soil temperature does not usually drop below 6 °C (although the end of 2010 recorded a prolonged period of snow, the first in living memory).

The island supports arctic, Mediterranean, and alpine plants side-by-side, due to the unusual environment.

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

Notable 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.

It was here he is said to have got inspiration for his plays The Playboy of the Western World,[7] Riders to the Sea, and many of his other works from stories he heard while on Inishmaan.

The house he stayed in, Teach Synge, was inhabited by descendants of the Mac Donnchadha family until the 1970s, when it began to fall into disrepair.

The library provides a reference and local studies collection with information on the heritage and history of the island.