Sea level and current observations made during a 2-month summer period in Delaware's inland bays are used for the examination of the tidal and subtidal variability in the bays. To first order, the coupled inland bays are found to be forced primarily by coastal sea level fluctuations at both tidal and subtidal frequencies. The observations suggest that the systems behave as low-pass filters in response to coastal forcing. Overall, tidal variance decreases sharply inside the bays, with the semidiurnal tides suffering significantly higher attenuation than the diurnal tides. The subtidal variability, however, experiences no appreciable attenuation within the bays. The systems are also found to be only weakly nonlinear in nature. A linearized frequency-dependent pumping mode model is developed, and results indicate that the model adequately describes the first-order response of the inland bays to coastal sea level forcing. ¿ American Geophysical Union 1988