Has anyone here been lucky enough to see the Severn Bore?

I had no idea of its existence until the other night when I was watching coast. For those that don't know, it is basically a wave that surges up the river in what looks like the wrong direction. On the TV it was spectacular so I'd love to see if in real life.

Does anyone know what causes it?

I thought it happened at high tide each day. It has been big enough to surf on occasion. Theres always canoeists on it.

Maybee the waves come up river, hit underwater rocks and bounce back the other way?

Here is some research I have done for you:
A Severn Bore occurs when a large amount of tidal water enters the Bristol Channel from the Atlantic sea.
The tide is then forced up in to the Severn Estuary , which becomes narrower as it progresses . This can increase the water up to anything of 15 meters ( 30 feet ).
Minsterworth is on of the key points of the Severn Bore and once the bore has reached this point the wave can be going a average speed of 17km per hour and can be up to 6 feet in height.
The width of the Severn narrows dramatically and the river becomes shallower thus causing the hold up of the tide and the waters begin to build up. The mass of water at the rear of the tide endeavours to overtake the leading wave thus causing a large bore to occur.

Where to see the Severn Bore
Best places to watch the Severn Bore are generally agree to be at Minsterworth, Stonebench and Over Bridge, before the river splits into two branches. These are limited areas thus car parking may be difficult on large bores.
The early stages of the Severn Bore can be seen at Epney, Newnham and Fretherne.
Always arrive early if you wish to see the Severn Bore as the times of the bores can vary up to 30 minutes ever way. Also on big bores a lot of people will be present thus traffic and parking might be a problem but well worth the effort.
Viewpoints at Minsterworth and the access is all privately owned so stick to the public footpath along the severn bank.
Be careful and do not get to close to the bore as traveling at 17km per hour the Severn Bore has more than enough power to sweep you away or the odd cow!

Remember the Severn Bore is a fantastic sight but just be careful

Yeah, which is what i said only in one sentence!

Mine is more detailed!

I have never seen the Bore but have heard about it many times. I also saw the program it was featured in and I liked how they compared it to the Northern Lights, as while it might not be as spectacular, it is an amazing quirk of nature.

I believe that it is more spectacular on the high Spring & Autumn equinox tides.
We used to get a very small bore, about 2 feet, at a tidal river near here. The estuary has altered now and it very rarely happens.