What I thought was excruciating about the Kursk, beyond Russia refusing foreign assistance for almost two days, is if it had been stood on end where it sank, the hull would have breached the surface of the water by over 170ft (sank in 330ft of water, hull length 505.2ft). fwiw, Arnaud Jerald holds the world record depth reached by a free diver, 367.5 feet.