This equestrian event has 2 4-player teams with long-handled mallets (not many horses in the water version)
[DOC] [TLE] Horse-riders' sport, 4 letter, crossword - CrosswordOpener [PAR] Company whose logo includes a horse ... Game in which each team has 8 heads 
and 24 legs ... Game played both on land and in water ... Game played with four-
foot-long mallets ...