Diving Chess is a chess variant, which is played in a swimming pool. Instead of using chess clocks, each player must submerge themselves underwater during their turn, only to resurface when they are ready to make a move. Players must make a move within 5 seconds of resurfacing (they will receive a warning if not, and three warnings will result in a forfeit). Diving Chess was invented by American Chess Master Etan Ilfeld; the very first exhibition game took place between Ilfeld and former British Chess Champion William Hartston at the Thirdspace gym in Soho on August 2nd, 2011. Hartston won the match which lasted almost two hours such that each player was underwater for an entire hour.