Wow. If that happened when it was submerged, the shockwave must’ve been tremendous. Think what it must have been like to be on that vessel when that hit. Wow.
The Kursk had it’s bow removed after recovery. The Russians claimed a collision with a NATO boat (US or Brit). Some conspiracy-minded analyst theorized that it took a MK-48 torpedo hit right in the control room.
Considering they were practicing a missile drill at the time against a Russian surface unit, I’ll stick with the likelihood of an internal explosion.