I didn't mean to scare you off the rivers. they can rise fast and people do die every year but mostly in the rainy season. Looks you were swimming in some fast current areas too. It's fun and challenging, just be aware of whats down the river a ways. these people were less than 20 feet from the top of a really high waterfalls, most made it to shore but these 4 people stuck together and ended up just 6-8 feet from shore holding a big bolder until overcome by the pressure.
I can't imagine the people there watching and not being able to help just a few feet away. I only saw the video and will never forget.