Herein we discuss the results of a study of the structure, evolution and break-up of an internal tidal wave under conditions of a steep shelf with a slope close to that of the internal wave characteristic. Measurements were taken in Navidad Bay on Mexico's Pacific Coast. We demonstrate that, under the conditions of homogeneous density stratification, the internal tidal wave releases its energy and collapses due to resonant excitation in a sequence of third tidal harmonics. Those harmonics generate multiscale vertical bilateral steps that follow at regular intervals and feature coherent oscillations in the form of vertical jets that cover the entire water column.