Until 1999, anyone could operate a boat, regardless of boating safety knowledge, experience or training. It is now a requirement that boat operators demonstrate their boating safety knowledge by obtaining proof of competency. 

Proof can be a completed Sail Canada Basic Cruising course as certified in your logbook or the Pleasure Craft Operator Card ("Boater Card") or a certificate on this list from Transport Canada. Certificates are valid for life.

If you hold any certificate on this list, you just need to make sure you carry your certificate on board. You may carry the original documentation or a copy of the certificate, as noted on this Transport Canada web page. 

You may also need other certificates, such as the marine radio certificate - Restricted Operator Certificate - Marine - required to operate marine radios, and a Toronto Port Powered Vessel Operator Permit to enter Toronto Harbour. "Recreational boaters operating a powered vessel within the Port and Harbour of Toronto must be in possession of BOTH a Powered Vessel Operator’s permit and a Pleasure Craft Operator Card."

For reference, here is the citation from the Canada Transport Act regarding proof of competency