Geograph - photograph every grid square

8:58am 15 seconds. Just as it passed us, the wave broke into a roaring, froth. The water behind the bore wave was very turbulent and could be seen rapidly running upstream with the wave. The surfers in the picture beforehand told us this would happen and some of the most repeated footage of the day on both Sky and BBC news were of these four surfers surfing up this stretch of the river.

It may seem that there are ripples ahead of the main wave caused by the wave itself - this is not the case. The bore wave is the actual shock wave of the tidal inflow and the ripples are caused by a boat just ahead of the wave. The river would be dead calm up until the moment the bore wave hits otherwise.