The major islets are: Ajelep, Aliej, Ailuk, Alkilwe, Barorkan, Biken, Enejabrok, Enejelar, Kapen and Marib.

Three main passes enter the lagoon through the western reef: Erappu, Marok and Eneneman.

As most local coral growth stops at about 45 m (148 ft) below the ocean surface, such a massive stony coral base suggests a gradual isostatic subsidence of the underlying extinct volcano,[3] which itself rises 3,000 m (9,800 ft) from the surrounding ocean floor.

Ailuk Atoll has a tropical rainforest climate, indicating consistently warm temperatures and high humidity.

Water and soil is the most limiting factor for plant growth especially for cultivated crops in the atolls.

The horns of this forest crescent extend along the passage beaches, usually with Suriana and Pemphis on the margins.

Common land birds include the Reef Heron, Golden Plover, Whimbrel, Bristle-thighed Curlew, Bar-tailed Godwit, Wandering Tattler, Ruddy Turnstone, Sanderling, Sharp-tailed Sandpiper, and Long-tailed New Zealand Cuckoo.

[9] First recorded sighting of Ailuk Atoll by Europeans was by the Spanish expedition of Miguel López de Legazpi on 10 January 1565.

[10][11] Two of its islets were charted as San Pedro and San Pablo, those being the names of the flagship ("capitana") and the "almiranta" (secondary ship or ship of the Admiral)[12] Ailuk Atoll was claimed by the German Empire along with the rest of the Marshall Islands in 1885.

In December 2020, Marshall Islands police found an abandoned 5.5-meter (18-foot) fibreglass boat that washed ashore at Ailuk Atoll with 649 kilograms (1,430 pounds) of cocaine worth an estimated US$80 million.

The Ailuk City Hall provides a space for community meetings and some basic administrative services.