Stream

• tidal flow

  The water current caused by the tides.

• undercurrent

  A current below the surface of a fluid.

• riptide

  A strong surface current flowing outwards from a shore.

Also contains

• high tide

  The tide when the water is highest.

• ebbtide

  The tide while water is flowing out.

• low tide

  The lowest (farthest) ebb of the tide.

• flood

  The occurrence of incoming water (between a low tide and the following high tide); "a tide...

• leeward tide

  A tide that runs in the same direction as the wind is blowing; "a leeward tide is dangerous...

• slack water

  The occurrence of relatively still water at the turn of the (low) tide.