The concept of sidemounting cylinders originated from cave diving in the UK, during the 1960s. During 'dry' explorations of Wookey Hole, the River Axe and other underground systems, divers occasionally encountered submerged passages that blocked further exploration. These cavers began incorporating scuba equipment specifically to progress beyond underwater areas. However, because they operated in very confined spaces, and most exploration remained primarily 'dry', they began experimenting and improvising with extremely minimalist configurations, minimising bulk, allowing cylinders to be easily removed and replaced, and retaining the capacity to squeeze through the tightest restrictions.