Rangel, M.O.; Dentinho, T.P.; Araújo, G.; Lopes, J.; Gonçalves, J.M.S.; Erzini, K. 2009. "Análise custo viagem de roteiros subaquáticos (de apneia) na Praia da Marinha (Algarve)". Revista Portuguesa de Estudos Regionais, 22:77-89.

The value of recreational snorkeling in defined underwater routes was evaluated for Praia da Marinha, Algarve. Travel cost technique was used for defying the value of recreational use and benefits of this natural resource. A total of 115 questionnaires were analyzed, based on surveys carried out from 15/07 to 15/09 of 2008. Regression analysis was used, with the number of dives as the independent variable, while dependent variables refer to different costs incurred during the trip and time spent on the activity weighted by a fraction of the declared income. The estimated average surplus was 5,0 € and the value of the three routes was of 600 €/year, which corresponds to a total value of 30000 €, considering a discount rate of 2% and the maintenance of the resource for many years. Assuming a carrying capacity of 1000 dives per year, the total resource rent per year is 5000 €, corresponding to a total economic value of 250000 €.