This article, using the zonal version of the travel cost method (ZTCM), provides the first economic valuation of recreational trips to Mont-Saint-Michel (MSM). The MSM was designated as United Nations Educational, Scientific and Cultural Organization World Heritage Site in 1979, and is the most visited coastal site in France. The potential effects on consumer surplus (CS) estimates of some aspects of the ZTCM are considered, namely the treatment of the multiple purpose/destination (MP/D) trips, the inclusion of the opportunity cost of time (OCT) in the recreation demand model and the heterogeneity in the preferences. The heterogeneity in the preferences is examined through a random parameters Poisson model (RPPM). The RPPM generalizes the standard Poisson model (SPM) by allowing coefficients of explanatory variables to vary randomly across geographical units rather than being fixed. Our results show that (1) substantial CS values are associated with the MSM; (2) excluding/ignoring MP/D trips result in biased CS estimates; (3) omitting OCT does not substantially bias CS estimates; (4) the RPPM provides richer information about the impact of explanatory variables on the demand for trips than the SPM, but (5) leads to statistically similar CS estimates than the SPM.