Croatian swimmer Veljko Rogosic died in a Split hospital on Tuesday aged 71 after a serious illness, the hospital said.
Rogosic's biggest endeavour was swimming a 171 km stretch from Sicily to Tunisia in 2008 when he was 67, which took him a little over 50 hours.
In 2005, he swam 1,000 km from Savudrija in northern Croatia to Prevlaka in the south, while the year before he swam across the La Manche.
Rogosic took part in the Olympics in Rome in 1960 and in Tokyo in 1964.
He swam for the former Socialist Yugoslav national team 203 times, was state champion 142 times and broke state records 51 times in 1,500 m and 400 m freestyle, 400 m and 200 m medley, and in 200 m dolphin.