The tide is fast near the sea surface and slow near the sea floor.

■Two tides

A tidal current in which the direction of the tidal current near the sea surface is different from the direction of the tidal current near the sea floor.
Dive quickly to the same water depth as the team leader and you will not be separated from the team.

■Other tides

In places where the seafloor topography changes significantly, such as large rocks, up-currents and down-currents occur.
Adjust buoyancy quickly to respond to the tide.