There are plenty of ways to die on a whitewater river, most of which are well understood. You can get trapped underwater by the branches of a downed tree, pinned in the sieve between two boulders, or stuck in the swirling flow of a hydraulic. You can bang your head on a rock, fracture your spine, or have a heart attack. But a substantial fraction of whitewater deaths don’t fit into any of those categories. They’re colloquially referred to as “flush drownings,” and no one is entirely sure why they happen.
A new paper in Wilderness & Environmental Medicine,