Diamond Lake is the name of at least nine different lakes in Ontario, Canada:

Diamond Lake, Kenora District Diamond Lake, Cochrane District Diamond Lake, Algoma District Diamond Lake, Sudbury District Diamond Lake, Hastings County Diamond Lake, Nipissing District/Sudbury District Diamond Lake, Timiskaming District Diamond Lake, Renfrew County Diamond Lake, Parry Sound District

See also List of lakes in Ontario

References