The Great Barrier Reef (GBR) is a vast iconic environmental asset covering an area of approximately 35 million hectares and as such is valued by people all over Australia, as well as overseas. While non-market values for the GBR will comprise both use and non-use values, the values of people who live closer and who can visit the GBR more frequently, are likely to be higher than those who live further away in more distant locations. The aim of the study outlined in this report was to estimate the values to protect the health of the GBR at the national level, and in doing so, examine the effects of distance decay on valuation estimates. A split sample choice modelling experiment was conducted in six locations: a regional town within the GBR catchment area (Townsville); Brisbane, the state capital approximately 450 km from the southern limit of the GBR and four other capital cities (Sydney, Melbourne, Adelaide and Perth) ranging from 730 km to over 600 km from Brisbane. The results indicate that the total national value for a 1% improvement in the health of the GBR ranges from between a low of approximately $433.6 million to a high of $811.3 million depending on the underlying assumptions made. There was some evidence of distance decay in values with most decline occurring once outside the home state, and little further decline occurring once away from the east coast. There was no evidence to suggest any difference in patterns of use and non use values but the values of the potential future users that were most influential in determining WTP estimates.