Natural spaces and the use thereof represent a certain value for society. This may be reflected in the revenue generated by activities such as tourism, implicit real estate prices, or the desire for environmental protection. Decisions taken by stakeholders tend to be based mainly on a comparison of these values with those of economic development projects. Although many approaches have been developed to provide a monetary value for the environment, the Delphi technique retained for the present study is based largely on the use of a meta-analysis to assign values to identified services. This process also allows a transfer of knowledge from the experts consulted. The technique was applied to the Saguenay–St. Lawrence Marine Park (SSLMP) (Québec, Canada), a unique, biodiversity rich site. The first step involved determining the ecosystem services provided by the SSLMP. These were then weighted and assigned a value in dollars per hectare per year. The results of this process estimate that the annual non-market value of the SSLMP lies somewhere between CAN $ 27.8 million and CAN $ 32.9 million.