Making love, not war?

We're trapped in the belly of this horrible machine, and the machine is bleeding to death.

They were probably chasing eachother and then, something went wrong. You know, boys playing with toys, who has the fastest sub?

"Common sense is the collection of prejudices acquired by age eighteen." (Einstein)

Playing hide and seek (presumably jointly with attack submarines). Which is good training for their real mission, which is (i) hide and shoot or (ii) seek and destroy.

In the long run, we're all dead. John Maynard Keynes

No you'd expect any submarine contact to take place at very low speed. The main source of noise from submarine are either from mechanical equipment inside the submarine, pumps, engines etc or from an effect called cavitation. This mainly occurs from the tips and forward edges of the propeller where small bubbles are created on flaws in its leading edge.  This can be minimised by reducing speed, so when attempting to run silently, submarines are generally limited to roughly 3 knots of speed or less, depending on surface design of propeller blades.

You'd only expect high speed submarine impacts from attack submariens, that use a technique that involves sprints then drifts to create an artificial baseline for triangulating acoustic targets while hunting other submarines.

Any idiot can face a crisis - it's day to day living that wears you out.

Another possibility is that they have detected each other, and both tried to simultaneously 'disappear' and find the other.

You mean like hide and go seek?

And I'll give my consent to any government that does not deny a man a living wage-Billy Bragg