Post updated: 27.05.2022.
Since the original sinking sound is so underwhelming I got myself into designing a new one. I originally made one for a loop as the game originally handles the sound.
Then I made a TWOS version as in twos, the sound is only played once instead of a loop, so it's almost twice as long and more sequential starting from creaks and groans, devolving into rumbling and the hellish screams of tortured metal ending with some deep underwater rumbles and bangs as the ship implodes, stuff gets torn apart, etc
Download here (mediafire)
The zip contains the optional choices both for loop and for twos type single-time play along with backups and a readme
Now go, sink 'em all and listen to their calls for help as the waves consume them
Credits:
Capthelm of Subsim
The Hollywood Edge Sound Effects Library
The Orchard Enterprises
Valve Corporation
And other freeware sources from youtube and SFX pages