The rise and fall of tide is accompanied by horizontal movement of the water called tidal current. It is necessary to distinguish clearly between tide and tidal current, for the relation between them is complex and variable.
For the sake of clarity mariners have adopted the following definitions:
Tide is the vertical rise and fall of the water, and tidal current is the horizontal flow.
The tide rises and falls, the tidal current floods and ebbs. The navigator is concerned with the amount and time of the tide, as it affects access to shallow ports.
Tides are superimposed on non tidal rising and falling water levels, caused by weather, seismic events, or other natural force. Similarly,Tidal currents are superimposed upon non-tidal currents such as normal river flows, floods, and freshets.