Im a huge fan of surfing, here in FL, we actually do a lot of river surfing.
Cool I've never heard of river surfing.  Does that involve a sail?
No basically the water flows over a rock in high volumes causing a wave behind it.
Interesting.  What rivers in Florida have the best river surfing conditions?
The Hillsborough River is very good for river surfing. Oddly enough, in Germany is where you can find the worlds largest urban river surfing spot.
Are there river surfing competitions?
the British Secretary of State for the Colonies, and thus controlled the pensions of the surveyors working in the American colonies, which included East Florida.
History.
Geological data suggests that the Hillsborough River has been flowing for about 27,000 years. Humans first made their way to this area 12,000 - 15,000 years ago.
In the late 18th century the watershed of the Hillsborough River was a land covered by a rich, old growth forest. Majestic bald cypress, longleaf pine, and sand live oak were hundreds of years
over a rock and creating a wave behind. It is a form of hydraulic jump. A river surfer can face up-stream and catch this wave and have the feeling of traveling fast over water while not actually moving.
River surfing conditions are created by a combination of underlying rock formations and specific water levels, i.e. not too much or too little water. Water flow is usually is measured in the SI-unit cubic meters per second (m/s) (alternatively in liters per second or cubic feet per