Strainer: The deadliest trap on the river! When water pours through the branches of a fallen tree, or through a pile of rocks or ice, it produces a strainer. Even with a gentle current, strainers are bad. They can pin you below the surface of the water and you can’t get out. If you realize you can’t avoid a strainer, climb on to it, climb over it! If you are swimming in the water, and about to wash into a strainer, swim headfirst as aggressively as possible toward it and climb onto, up and over it.