Marilyn Bell
This plaque is dedicated to the honour of Marilyn Bell, a Toronto, Ontario girl who on Sept. 9th, 1954, at the age of 16 years, performed the magnificent athletic feat of swimming the full width of Lake Ontario, thus being the first know person to have accomplished this arduous task, of which all Canadians are justly proud.
Plaque via Alan L. Brown's site Toronto Plaques. Full page here.