This is where I stuck my head yesterday - the Thames.
As part of the kayak course did an x-rescue and one of the rolls in its very murky brown waters. And with the nose clip falling off while upside down ended up swallowing much more than would like.
Actually biggest danger was banging my head - at low tide the river is very shallow indeed.
If there's a lull in posting you'll know to blame the Thames lurgy!