Tidal harmonic constituents for Praia da Enseada (# PE) and Port of São Francisco do Sul (# PSFS) were assessed to characterize the local astronomical tide, as well to evaluate the shallow water effects on the tidal propagation to the interior of the Babitonga Bay. The sea level at # PE were monitored with a pressure tide gauge during June to December, 1996. From this data set, 48 tidal harmonic constituents was determined using the harmonic method for tidal analysis. The 32 harmonic constituents for the # PSFS were obtained with the Diretoria de Hidrografia e Navegação. Considering these information, the tide at the Babitonga Bay is classified as mixed, with semidiurnal dominance and diurnal inequalities, with Form Number of 0.32 for # PE and 0,29 for # PSFS. Nonlinear effects results in the amplification of the astronomical constituents towards the interior of the bay, showing hypersynchronous behavior. Some harmonic constituents increased about 2 to 7 times, and all presented around of 40 minute phase shift. Despite of the astronomical constituents amplification, there are also an asymmetry on the wave propagation, with flood dominate in bay. The role of the channel constriction effects over the bottom friction was clearly observed by the harmonic constituents speed increase towards the bay. The Babitonga Bay presents a natural oscillation period about 3,6 hours resonance with some of shallow water components. This effect can be a significant processes in the increasing of the astronomical components.