The longest Severn river is in Ontario, draining into Hudson's Bay. I also knew of another Severn River in Ontario, the one that forms a small part of the Trent-Severn waterway. Interesting to know there is another in Wales. Also, you might want to consider changing that answer.
Thanks for that, now changed! The one that flows through England and Wales is the UK's longest river and possibly the source of the name for the other Severns around the world.
Great quiz. Thanks. IMO it would be improved if you could add more rivers that flow through multiple countries - that would make it more challenging. But I suppose there aren't that many options. The Parana and the Irrawady spring to mind.