I wouldn't be too sure that volunteer divers will be a component of the Ripley's Aquarium in Toronto.
Legislation in the US enacted in 1982 exempts scientific divers, including aquarium divers, from the OSHA requirements. In Ontario, legislation enacted in 2004 specifically holds scientific divers, including aquaculture divers, to the same Ministry of Labour standards as commercial divers, equivalent to CSA Standard Z275.4 -02. Therefore, the training and cost requirements will be significant. That is why there are no volunteer divers at Marineland in Niagara Falls - a virtually identical type of operation.
It really is a shame. I've been volunteering at the Aquarium of Niagara in New York for 6 years and always enjoy my time in the tank!