The Athens Dream, a 220-page special issue of Black+White magazine, retails at A$32.95 (US$22.74).
Australian athletes also shed their clothes for the Olympic edition of the magazine in 1996 and 2000.
Shaven-headed Klim is a former 100 metres butterfly world record holder but has only qualified for the 50metres freestyle relay at the Athens Games in August.
Klim posed with fish in warm water.
"They were smelly and slimy. At the end of the day I felt quite liberated. I was ready to go again," said the 26-year-old, who won two relay golds at the Sydney 2000 Games.