I can still hear the scream.

From Trying to Please by John Julius Norwich.  Page 128.  

At the end of September we left our dry dock in Portsmouth and headed—with perhaps two dozen or more other ships of the Home Fleet—for the wide ocean. The crossing took us just over a fortnight, owing to various exercises on the way; during the second week when the weather had grown warmer, the entire fleet would stop for an hour in midafternoon, so that all the ships’ companies could swim over the side; it was strange, but curiously invigorating, to know that one was immersed in water two thousand miles away from land and perhaps five miles deep. Aboard Cleopatra we had only one serious mishap, when one of our Leading Signalmen dived straight into the middle of a Portuguese man-of-war. After a week or two in the sick bay he recovered, but I can still hear the scream.