Strainers are obstacles in a river or creek that water can flow through, but that a boat or a body could not. Downed trees on the riverbank are the most obvious strainers, but not the only ones. If you dump in a swift-moving river or creek, the rule of thumb is to float on your back, head upstream and feet up, so you can prevent foot entrapment and see what’s coming. But when what’s coming is an unavoidable strainer, it’s time to take matters into your own hands. Turn over on your stomach, face downstream, and swim powerfully towards the obstacle. Try to outpace the current. As you approach the strainer, time your final strokes and a powerful butterfly kick to get your head and chest out of the water. Place both hands on the obstacle and push up, kicking hard. You want to launch yourself up and over, or up and through the strainer, so fight your way clear.