Tide and tidal current distortions were examined in Hampyung Embayment, a shallow, semidiurnal tide-dominated bay with large tidal flats, via in situ monitoring. Harmonic analyses reveal that the shallow-water constituents of the tides and tidal currents are strong in this restricted setting relative to on the open coast. In particular, the amplitudes of the shallow-water currents constituents (M4, MS4, M6, 2MS6) are three times greater than those of the diurnal constituents (K1, O1). The quarter-diurnal (M4 + MS4) and sexta-diurnal (M6 + 2MS6) current amplitudes account for >35% and >17% of the semi-diurnal current (M2 + S2) amplitudes, which account for >42% of total amplitude. The MS4 current amplitude is as important as that of the M4 amplitude in the middle of the bay. Such strong generation of shallow-water velocity constituents induced by non-linear processes leads to an ebb-dominated tidal regime with double-flood current-velocity peaks.