 From a point relatively close to the areas of the cave open to the public, the cave-divers' descent into Sump 1a begins through a tight passage known as Dire Straits.The bottom of that passage opens into the river passage, which is several meters across.This has been explored for downstream, whilst upstream a dive of brings the diver out in a long chamber named Lloyd Hall (which can now also be reached by an alternative, dry, route).