Having recently enjoyed the delights of Greenland, which involved a couple of slightly chilly river crossings, I would now not be without a pair of Crocs. Strip off your boots and socks to keep them dry, slip on the Crocs and across you go. They were very good in the rivers, providing a firm footing even on the slimier of the rocks - an important consideration when carrying a heavy pack!
I had always been sceptical about them but am now converted. They weigh next to nothing and have the added bonus of being a really useful, comfortable camp shoe when you arrive at your destination, obviating the need to wear your boots for the whole of the day and giving your feet a well-earned rest. They dry quickly and are machine washable. Apart from their appearance, what's not to like?
As ever, I'm just a satisfied customer...