[3] He represented Croatia at the 2008 Summer Olympics, and has claimed multiple Croatian championship titles and national records in both the freestyle and butterfly (50 and 100 m).

Leading up to the Games, he finished with a third-place time in 52.61 to dip beneath the FINA A-standard (52.86) by 0.25 of a second and earn a direct Olympic selection to the Croatian squad at the USA Swimming Grand Prix in Columbus, Ohio.

[5][6] Coming from third at the halfway turn on the outside in heat six, Puninski faded down the stretch to hit the wall in dead-last with a 53.65.

[7] At the 2008 European Short Course Swimming Championships in Rijeka, Puninski set a Croatian record of 22.63 seconds in the semifinals of the men's 50 m butterfly.

[8] He also won a bronze medal as a member of the Croatian team in the men's 4×50 m freestyle relay, with a time of 1:23.68.