In this paper the results of a choice modelling experiment to value increased protection of the Great Barrier Reef in Australia is reported. There are very few previous studies that identify protection values for the Great Barrier Reef, making it difficult to evaluate whether the community benefits from future additional protection measures are larger than the costs involved. The valuation experiment that has been conducted is novel in two important ways. First, different management policies to increase protection have been included as labels in the choice experiment to test if the mechanisms to achieve improvements are important to respondents. Second, the level of certainty associated with predicted reef health has been included as an attribute in the choice profiles, helping to distinguish between outcomes of different management policies. The results show that protection values vary with the policy scope of the improvements being considered. Values are sensitive to whether protection will be generated by improving water quality entering the reef, increasing conservation zones or reducing greenhouse gas emissions, and the level of certainty of outcomes. The average household willingness to pay for five years for each additional 1% of protection is approximately $26.37 when the broad management options to generate improvements were included in the choice sets. These results can be extrapolated to a total value held by Queensland households of $132.8M to $171.5M per 1% improvement, depending on the assumptions used about the discount rate.