Bathymetric representation in Marine GISs (Geographic Information Systems) can be realized through 3D models: using data obtained from maps (such as spot heights and contour lines), continous surfaces representing sea bottom are produced with applications of interpolation algorithms. Even if the same data set is used for all applications, different results are obtained in order to the different formula that distinguish each method from the others. In this paper different results obtained with the application of some interpolation methods are considered: using 3D Analyst (ArcGIS 8.1, ESRI) and a set of data derived from nautical chart, in scale 1:60.000, concerning an area within Gulf of Naples, eight 3D models are built, such as one TIN (Triangulated Irregular Network) and seven DEMs (Digital Elevation Models), of which four generated with IDW (Inverse Weighted Distance), one with spline and two with kriging. Two grids containing sixteen points (all within initial chart data set in the first case, coinciding with regular grid in the second) are used to compare height results supplied by different models).