A planet that hosted the bat'leth competition from which Worf was returning in 2370 when he began slipping between parallel quantum realities.
Forcas III is a planet mentioned in the Next Generation episode Parallels.
Worf travels there alone by shuttlecraft to take part in a bat'leth tournament and wins champion standing, bringing home a trophy. On the way back his shuttle passes through a quantum fissure.
From then on small details keep changing. In one version of events he finished ninth; in another he never went. The trophy and his memories of the contest are among the first signs that he is moving between realities, a problem solved only when he retraces his course in the original shuttle.