there is a large development of a SCUBA diving industry in several coastal destinations of the Mexican Pacific (Ramı ´rez-Cordero 2008; Alonso-Domı ´nguez 2009; ReyesBonilla and others 2012). The Isabel Island National Park (IINP) is one of the 19 MPAs of the Mexican Pacific. However, only the terrestrial portion of this island is officially protected, leaving the adjacent marine area without protection. Moreover, no management strategy currently exists for the marine environment, and the TCCs of the marine and terrestrial areas of public use are unknown. It is a small island with a lodging station used by park rangers, scientists, and frequently by tourists including SCUBA divers. The number of recreational visitors to the island has increased in recent years; however, it is relatively low (*1,000 dives per year) probably because of the lack of infrastructure. Certain tourists come to the island on their own vessels, such as sailboats and yachts, whereas others hire authorized tourism service providers (Rı ´os-Jara and others 2003). Given the risks associated with human activity, it is absolutely necessary that recreational activities on Isabel Island be conducted in accordance with an adequate set of rules and monitoring, as the distinct areas of the island may suffer impacts of different magnitudes from tourism. To address this issue, the present study seeks to provide elements that contribute to the generation of an ecotourism management strategy that is consistent with the conservation goals of the marine park. These elements include proposals for underwater trails and estimates of the specific TCC for each trail, considering not only the environmental characteristics but also the economic and social aspects of trail development. This information should help establish mechanisms governing the participation of actors connected to the island and thereby contribute to a pertinent ecotourism proposal, which would be extremely important for the continued welfare of IINP.