The Waimarie was "fired up" for a special event last month, the 60th wedding anniversary of Don and Dawne Bullock.
Lifelong residents of the area, the diamond couple were joined by 75 family and friends from across the country and a grandson from the United Kingdom.
"When approached by family members as to whether the wintered Waimarie could be fired up for a short trip up the river for our 60th wedding anniversary they willingly said 'yes'" wrote Mr Bullock.
He said the May 28 celebration was a "unique venue for a special event" and thanked the "wonderful people who run the Waimarie Riverboat."
Mr Bullock said grandchildren, great-grandchildren and others were able to go down to the warm engine room and learn all about the steam engine while other guests mingled and enjoyed the experience above decks.
"Pigeons released carried notes back to the riverboat museum where devonshire tea, scones and savouries were enjoyed."
He said he and his wife could "confidently say it was an afternoon of special memories."
"Thanks to Marion, Captain Trevor Gibson, crew and all concerned for being so professional and pleasant."