Not terrible. The single note you held throughout was more annoying than suspenseful, it actually made it difficult to listen through. If I had that come on during gameplay I'd pause, turn off the music and never turn it on again.
The instruments seemed a bit too bright and a bit clean for me as well. Especially the horror style string strikes (1:13 is an example). For jump scare media like horror films it's OK, but for the blind stress of being depth charged 100 meters below the sea not so much for my tastes.
The swell at 1:32 was nice, but somewhat distracted from by the even higher pitch single background note throughout.
I think if you got rid of that one note and had more silence at parts it would be more suspenseful. Or even replacing the high note with something lower, more rumble. The swell, followed by some low note or tympani style percussion then nothing for a few beats might work.
Maybe try to capture the feeling of silence on the boat with just creaks and bubbles with the ever shifting background sound of the ship screws above. Growing louder and closer till you hear the splash of the charges then nothing till the muted implosion of the attack.