Sure! Why not? You jump in and catch the log as it shoots down the stream. You wrap your arms around the log and look ahead of you. Oh no! The bridge is too low! You'll scrape your back!
Thinking quickly, you hold your breath and roll underwater just in time to clear the bridge. Then you roll back over and hold on tight! You go around a curve and down a long strait stretch. This is like the best waterslide ever! You are approaching an S-curve when you feel something living brush past your feet. You put your feet down in the soft ground, trying to slow yourself and see what just touched you. You can feel the log trying to shoot out from beneath you, and your legs aren't quite strong enough to make you stop floating down the river.
Suddenly from behind you a great dark shape leaps from the water!