These words express the fear that Douglas had in his mind when he went down the pool the third time.
He had swallowed a lot of water and was in a state where he could make no effort to jump up.
His legs felt limp, he began feeling numb and there was blackness all over his brain.
He felt drowsy and wanted to go to sleep.
Final Answer:
The lines depict that Douglas had lost his physical strength and hope.
