I used to hear them roar right through the hull of my boat. Could have been a half mile away, but the sound travels underwater.
Once I was feeling around the bottom beneath the boat with a magnet tied to the end of a boat hook, to try to retrieve some Vice-Grip pliers I'd dropped overboard when something grabbed the hook and gave me big yank back. Decided to forgo retrieval that day.
One night I had to go overboard in the middle of the Peace River in SW Florida to cut loose a crab pot line wrapped around the prop and shaft while others aboard scanned the area for gators with a single flashlight. That was a very long 5 minutes.