This fine photo by Michael O’Sullivan shows members of the Castlebar Camera Club busily at work, photographing nearly 100 metres below the surface in the Doolin Cave, Co. Clare, where a huge stalactite suspends naturally from the roof of an underground cavern. This geological wonder is the largest of its kind in the Northern Hemisphere; it is 7 metres long and weighs an estimated 10 tons. The stalactite  has taken many millions of years to form and it continues to grow continuously as the water dripping from its surface leaves behind infinitesimal particles of calcite each day. It is a beautiful and fascinating sight, which was first discovered in 1959 but only recently opened to the public.