In order for the tide to rise and fall at a given location, water must move from one place to another. These horizontal movements of water are known as tidal streams.
In many areas frequented by sea kayakers, steep rocky coastlines make the height of tide less of a concern. However, tidal streams often run at 2-3 kt and sometimes much faster. Given that tidal streams can move as fast as we can paddle, they clearly need to be accounted for in our plans.
This map below shows the directions of the main flood tidal streams (i.e. those that occur in the run up to high water at Dover and Liverpool) around the UK.