Goalball is a team sport designed for blind athletes which was devised in 1946 to help the rehabilitation of World War 2 veterans.
Participants compete in teams of three and try to throw a ball that has bells inside into the opponents goal. Games consist of two 12 minute halves, and all players must wear blindfolds to ensure that partially sighted and completely blind players are on an equal footing.
Rules state that the field of play must be 18m by 9m wide with goals spanning the entire width of the pitch. The ball is 30 inches in circumference and has eight holes with noise bells embedded within. Quiet is required from the players, coaches and spectators during play