It is roughly rectangular and has more than a hundred small islands on its landward side; Ireland's best example of sunken drumlins.Umhaill's last and most famous ruler was Grace O'Malley (Gráinne Ní Mháille), nicknamed "the pirate queen".During the Irish Civil War in July 1922, 400 Free State troops were landed at Clew Bay to take Westport and Castlebar from Anti-Treaty forces.[citation needed] In 2024, the discovery of a submerged late Bronze Age fort from the depths of Clew Bay was announced by a team from Connemara and Mayo County Council.[citation needed] This chart shows the relative positions of the islands, sandbars, and rocks in the eastern half of Clew Bay.