Whenever a movie has a scene with a submarine in it, you can bet your bottom dollar that this woefully overused sonar ping will be pinging away in the background, as if to say, "Hey guys, in case you hadn't noticed, this scene is underwater, and they're in a submarine." It's always the exact same sound, which is actually pretty daft considering the sonar signature can be altered by those on-board the ship, and it's extremely unlikely that every ship in the history of the world would therefore decide on the same noise. Plus, a sub's active sonar is rarely ever used in duty due to the fact that it will give away a sub's position extremely quickly, so movies have just been getting this one completely wrong for decades...