German deep-sea diving suit brought from Kiel for examining the lost submarine 'M1'. On 21 November 1925, while on an exercise in the English Channel, the 'M1' subrine sank with the loss of her entire crew, the crew members appear to have tried to escape by flooding the interior and opening the escape hatch, but their bodies were never found. At the time the subrine was lying to deep to use ordinary diving apparatus. So the decision was made to ask for the assistance of Messrs. Neufeldt and Kuhnke, of Kiel, who specialized in deep-sea diving apparatus.