Currents
tidal current
Tidal Currents
Tidal currents form when incoming or outgoing tides force water through a narrow passage. Since tides move in and out several times a day, the direction and force of tidal currents changes throughout the day.

Currents of this type are often too strong to swim against, so careful planning is required before diving in areas with tidal currents. The safest diving is during slack tide, which is the period when tides are about to change direction.