Alexandra resident Bob McNeill travelled free of charge because he was the same age as the Earnslaw.
All people who are the same age as the vintage steamship cruise without charge.
Scones and pikelets with jam and cream, tea and coffee and cake were served.
The birthday bash raised $1120 for Jigsaw Central Lakes, formerly the Wakatipu Abuse Prevention Network.
Miss Maclaren said the trip was "a delight".
"There was plenty of history crossing the lake [yesterday] morning, with a couple of people in their 90s on board. We had a good, hearty sing-a-long and there was a wonderful atmosphere."
The birthday starts the countdown to the popular Queenstown attraction's week-long centenary celebrations in October next year.