Somers started climbing in 1974 at the age of 27, and became one of the leading rock-climbers in Ireland in the 1970s, establishing significant new routes in areas such as Ailladie (The Ramp), Fair Head (An Gobán Saor, Fáth mo Bhuartha), Muckross Head, and Tormore in Co. Sligo. In 1983, he became the first Irishman to have climbed the six great north faces of the Alps. He participated in Irish expeditions to Himalayan peaks Changtse in 1987, Manaslu in 1991, and Everest in 1993. He has also climbed in the Andes and other greater ranges.