A national park website extends (in certain way) a physical national park. It does not have a physical location so its elements and information can be appreciated from anywhere in the world. Usability is a well-known concept, for decades. User eXperience (UX) is a broader concept that encompasses usability. The usability and UX evaluation are important tasks to perform when developing any kind of websites. In this regard it is important to evaluate whether a national park website is intuitive, easy to use, and allows users to complete their objectives. National park websites have their own features that differentiate them from other systems, so it is necessary to use a set of appropriate heuristics for these types of websites. The article presents a set of 14 heuristics to evaluate the UX of national park websites. The heuristics were developed using the methodology proposed by Quiñones et al. . To validate and refine the UX heuristics for national park websites, we performed two iterations. In the first iteration the heuristics were validated through heuristic evaluation and expert judgment (survey), while in the second iteration the heuristics were validated through user tests (co-discovery and focus group). Based on validation results, we concluded that the proposed set of heuristics are effective.