This equestrian event has 2 4-player teams with long-handled mallets (not many horses in the water version)
Sport not seen in the Olympics since 
1936 ... but played on horseback using long-handled mallets and a wooden ball
... [DOC] [TLE] Horse hockey - definition of Horse hockey by The Free Dictionary [PAR] A game played by two teams of three or four players on horseback who are 
equipped with ... horseback using long-handled mallets (polo sticks) and a 
wooden ball.