Sentence 1: The river was full people rafting down on inner tubes. 
 Sentence 3: He drifted for miles down the river before he hit some rapids 
 Sentence 4:  He awoke in a panic and paddled ashore 
 Sentence 5:  The guy looked around and wondered how long he was asleep 
 Option 1: One guy was so relaxed he fell asleep in his tube. 
 Option 2: One guy kept awake on his tube.