The Chan similar to aral Island Marine Reserve (CIMR) is a protected area in north-central Chile that is a feeding area for large cetaceans such as fin, blue and humpback whales. However, a number of studies indicate that a large proportion of whale sightings occur outside this protected area. Thus, an increase in the size (or dimension) of the protected area has been suggested. This requires ensuring compatibility of the protected area with economic activities which take place there, especially fishing, tourism and diving. This study proposes a strategic plan for expanding the CIMR area developed using the decision-making algorithm MARXAN. We proposed three con-servation scenarios: Scenario 0 divided the proposed area into planning units (PU) classed as either"obligatory" or "available"; Scenario 1 in which all PUs were "available" and Scenario 2 with the PUs "obligatory", "available" and "suggested". The results suggest that Scenario 2 is the most favorable for conservation, since it supports increasing the current area of the reserve, adding a second nautical mile around the island. This would create an area sufficient to fulfill the conservation goals for the three whale species (30% of the feeding areas for blue and fin whales and 10% for humpback whale) without producing an impact on the current activities in the CIMR.This zoning proposal provides a roadmap for the development of protected areas based on scientific baseline, including the participation of local communities that ultimately should validate the proposal to successfully support its implementation.