Outlying islands are affected by the environment and economy, and fishery resources are the first to experience these impacts. Therefore, it is necessary to actively and effectively transform traditional fisheries in outlying islands. This is the case in Penghu County (Penghu Islands), located on the outlying islands of Taiwan. The transformation to recreational fishery can increase the additional income of traditional fisheries during the fishing moratorium through the development of recreational fishery boats by fishermen. Recreational fishery means the fishery using fishing vessels for recreational purposes or for passengers to harvest aquatic organisms on the reef or to engage in sightseeing on the islets. Therefore, this study will explore the key factors for the successful route planning of fishermen who switch to recreational fishery boats to assist the fishermen in successfully transitioning and enabling recreational fishery to flourish. In the research, using the method of the Analytic Hierarchy Process (AHP) expert questionnaire, it was found that the key factors affecting the route planning of recreational fishery boats are “boat conditions”, “berthing conditions”, “operating environment”, and “sightseeing potential”. After the expert questionnaire, a weight comparison of each level was performed, and it was found that “operating environment” was the most important factor, followed by “tourism potential”. However, the key factors of the “natural environment” and “cultural environment” are more important under the influence of the “operating environment”. Under the influence of “tourism potential”, “attractiveness” is a key factor, as is the “accessibility” factor. In this study, the four main fishing ports in Penghu County were also used for empirical discussion. The study results showed that Magong Fishing Port was the first choice for transformation, followed by Chikan Fishing Port. The results of this study can be used as a reference for fishermen and officials in developing a subsidy scheme for fishing boat operation, and they can be used as a reference for transforming traditional fisheries in outlying islands into recreational fishing to develop recreational fishery boats and leisure tourism industries. This research can help fishermen to attach importance to the development of recreational fishing activities and promote the stable growth of the fishery industry environment.