Answer: in my lawn chair.
Step-by-step explanation: a misplaced modifier, is a modifier in a sentence or in a paragraph that is placed in a position that might produce some kind of misunderstanding or just make the sentence to be unclear. In the given paragraph the misplaced modifier is "In my lawn chair" because in the sentence "I could not see the pool in my lawn chair" it seems that the pool is in the lawn chair, one way to correct this sentence would be "From my lawn chair, I could not see the pool."