The funnel-shape of the Bristol Channel is perfect for the formation of tidal bores in the upper reaches of the Severn Estuary near Gloucester. The high tide (especially spring tides) enter the river as a wall of water called a bore. This then breaks like a wave against the banks or in the shallow parts of the river.
Tidal bores also occur in the Petitcodiac River at the northern end of the Bay of Fundy, in the Amazon River in Brazil, and in the Fuchun Jiang in China (reported to have the biggest bore wave at around 15-20 feet) as well as some other European rivers.
Where to watch or ride the bore
Newnham is the first stop to see the bore. As the bore travels about 5 - 10 mph, after the bore has passed you have plenty of time to drive to Minsterworth to see it pass there and then to continue on. Probably the best place to view the bore is at Overbridge where you can stand on the bridge and watch it travel under the bridge and up river.
Riding the bore
As riding the bore is popular, you will find yourself jostling with a number of canoeists, jet skis, inflatables and other surfers in the river while waiting for the bore to arrive. Because the bore wave is slow and weak catching it can be a problem even if you have a longboard.
If you do catch it you will find yourself line abreast with the other lucky contenders (between 6 and 10 people) moving forward. As the bore travels up river around corners the wave surges from one bank to another and you need to be where the concentration of the surge occurs to ride the bore any distance.
The ugly part of bore riding is after you lose the bore and you are being towed along with all the debris (trees, plastic rubbish and dead animals!) that gets sucked along behind. You have to approach the muddy bank (in the 10mph current) and grab a hold and pull yourself up on the bank - yuck, yuck, yuck. But if you are quick you can run back to your truck, race up the road and catch it again!
Maisemore is only of significance as there is a weir which the bore cannot pass and so the bore ends here.