In the 6ish hours between high tide and low tide (or vice versa) the water doesn't flow evenly, It turns gradually, then flows heavier and then eases up again before turning back.
And we're currently at that point in the year between the 6ish monthly low and high tides of light, where strange strong currents of the light come streaming powerfully past you and can dislodge your footing or spin you round.