Diving, developed from gymnastics in the 18th century, is the sport of jumping or falling into water from a platform or springboard, sometimes while performing acrobatics. Diving originated from people amusing themselves by jumping and diving from natural features (rocks and cliffs) or from structures built for other purposes (piers and bridges) early swimming and diving clubs were based on ponds. Diving was a traditional speciality of the guild of salt boilers, called Halloren to practise certain swimming and diving skills. The Halloren used to perform a series of diving feats from a bridge into the River Saale. Diving was popularised by the Swedes and the Germans in the 18th and 19th centuries. In Sweden wooden scaffolding was erected around many lakes, inviting courageous fellows to perform diving feats. Somersaulting from great heights and swallow-like flights of a whole team are common.