Čolak was the 2011 CMAS World Champion in dynamic apnea with fins, with a 250 m swim, setting a new CMAS world record, his fourth CMAS world record in his short career. On October 16, 2011, he became the AIDA International world champion in the same event (AIDA World Championship in Lignano, Italy), and set the new AIDA world record of 273 m, surpassing the previous record of 265 m held by Dave Mullins. At the same event he won two gold medals, one silver medal and set a new world record.
