The Galapagos Archipelago is one of the most attractive destinations for ecotourism in the world. The unique biodiversity on the islands attracts tourists and scientists from all over the world and tourism arrivals have been growing rapidly since the 1980s. The development related to the growing tourism industry threatens the endangered species on the Galapagos that attract over 200,000 tourists annually. To assess the sustainability of these developments, WWF Ecuador commissioned Wolfs Company to analyse various tourism growth scenarios using an extended cost-benefit analysis (CBA), in which economic and environmental costs and benefits are incorporated. The three analyzed scenarios are: rapid growth (8 percent increase per year), moderate growth (7066 visitors extra per year), and no growth. Conclusions – Both national and international tourists are willing to pay for additional nature management. – Tourists are not willing to return to a Galapagos that is more crowded or has a degraded natural environment. – Rapid growth of tourism only benefits the Galapagos in the coming 5 years, while controlling the number of tourists will continue to be beneficial in the long term. Recommendations – Uncontrolled rapid tourism growth should be avoided. This appears as the least profitable scenario. – Develop a tourism growth plan that will manage the number of tourists arriving to the Galapagos Islands to remain within the Acceptable Visitors Load (AVL) established by the Galapagos National Park.