This paper attempts to develop criteria and indicators (C&I) for measuring the sustainability of ecotourism activities in Penang National Park (PNP) in Malaysia. In carrying out this objective, a Delphi process with Content Validity Ratios—a non-parametric tool—for generating a consensus for C&I sets was adopted with 30 academic and non-academic experts in sustainable tourism, ecotourism, and forestry. After four rounds of discussion, the panel members reached a consensus on a C&I set which consists of ecological (three criteria and seven indicators), social (three criteria and eight indicators), economic (two criteria and four indicators), and institutional (one criterion and two indicators) factors for ecotourism management. A consistency reliability test was also conducted, and the Cronbach’s alpha values of criteria and indicators were reported to be acceptable. This C&I set enables the provision of a suitable approach for managing ecotourism in a sustainable manner in Penang National Park. It can serve as an instrument for the sustainability evaluation and monitoring of ecotourism management in PNP by the Department of Wildlife and Tourism Organization in Malaysia. The proposed approach and the resulting C&I could be resonated with other national parks as ecotourism destinations with similar relevant characteristics of the PNP. © 2020, Springer Science+Business Media, LLC, part of Springer Nature.
