The travel cost method (TCM) is a widely used non-market valuation technique in ecological economics for estimating the economic value of ecosystems, natural resources, and recreational sites that do not have a market price. This method is particularly useful for assessing the recreational benefits provided by natural sites such as national parks, lakes, forests, and wildlife reserves. The fundamental premise of TCM is that the time and money individuals spend to travel to a site represent the implicit price they place on accessing and enjoying that site. By analyzing these expenditures, economists can infer the value that individuals attach to the recreational experience offered by the site. The travel cost method is rooted in the concept of demand for recreational sites. Just as consumers reveal their preferences through purchasing decisions in a market, visitors to a recreational site reveal their willingness to pay through the costs incurred in reaching and enjoying the site. These costs include direct expenses such as transportation fares, fuel, entrance fees, accommodation, and food, as well as indirect costs, notably the opportunity cost of time spent traveling. By aggregating these expenditures and linking them to the frequency of visits, researchers can construct a demand curve for the recreational site, thereby estimating its economic value. There are two main approaches within the travel cost method: the single-site model and the zonal travel cost method. The single-site model focuses on one specific location and measures the relationship between the number of trips individuals make to the site and the cost of visiting. Researchers collect data from visitors regarding the number of trips they make over a certain period, their place of residence, travel expenses, and demographic characteristics. Using this data, a demand function can be estimated, typically through regression analysis, where the number of visits is the dependent variable and the travel cost and other socio-economic factors are the independent variables. This demand function allows for the calculation of consumer surplus, which represents the economic value of the site to its visitors over and above the actual expenses incurred. The zonal travel cost method, on the other hand, divides the area surrounding the site into concentric zones based on distance or travel time from the site. The number of visits from each zone is recorded, along with the average travel cost from that zone. By analyzing variations in visitation rates with respect to travel costs from different zones, researchers can estimate the demand curve for the site. This method is particularly useful for larger or regional sites where visitor behavior may differ significantly