He also competed in the 1931 Manly International 500 Endurance Swimming Contest that was the first professional swimming contest of its kind in Australia as well as a charity swim for the Manly Hospital Citizens' Relief Fund. 60 swimmers from England, America, Italy, New Zealand and Australia, including 14 women, Mercedes Gleitze and Lily Copplestone, competed in the non-stop competition in January 1931. The competitors were fed with liquid food through a tube provided by assistants from a boat. The food consisted of chicken broth, milk, and chocolate in liquid form.
Zibelman claimed the record for continuous swimming by completing 100 consecutive hours, four days four hours 15 seconds in a swimming pool in Hawaii. In 1937, at the age of 44, he swam 145 miles down the Hudson River from Albany to New York City, supposedly for 148 consecutive hours. After six days in the chilly waters, his torso slathered in grease to retain heat, he called it quits at the 129th Street ferry dock in Manhattan.
In 1937, he boldly suggested his next attempt would be to swim from Key West, Florida to Havana, but newspaper coverage of Zimmy's exploits was limited to his 288 miles downstream swim in the Hudson River in 1938 in 74 hours to join the 24-hour club.