Clarence Giles was a 45-year-old livestock auctioneer who completed the greatest distance covered in a continuous open water swim where he traversed 288 miles from Billings, Montana to Glendive, Montana in the Yellowstone River in 71 hours 3 minutes, finishing on 4 July 1939 according to the Guinness Book of Records. He broke the records of Pedro A Candiotti (who swam 281 miles down the Parana River from Santa Fe to Zarate in Argentina in 84 hours in 1933) and Charles Zibelman (who swam 145 miles down the Hudson River from Albany to New York City for 148 consecutive hours in 1935).
“The toughest part of the swim was a surprise to me, just above the Buffalo rapids where the water pitched downward sharply for 75 feet. There was a whirlpool at the bottom and I got caught in it and smacked around pretty hard before I could work my way out,” explained Giles to the Lawrence Journal-World in 1939. He hit all kinds of wood and boulders as he swam and drifted at a pace of 3.6 miles per hour and stopped only once for 10 minutes en route while his escort car was stalled.