Editing Slack tide (section)

==Implications for seafarers==
For [[Scuba diving|scuba divers]], the absence of a flow means that less effort is required to swim and there is less likelihood of drifting away from a vessel or shore. Slack water following high tide can improve underwater [[visibility]], as the previously incoming tide brings clear water with it. Following low tide, visibility can be reduced as the ebb draws silt, mud, and other particulates with it.  In areas with potentially dangerous tides and currents, it is standard practice for divers to plan a dive at slack times.

For any vessel, a favourable flow will improve the vessel's speed over the bottom for a given speed in the water. Difficult channels are also more safely navigated during slack water, as any flow may set a vessel out of a channel into danger.