The tragedy of the Titan submersible still has more questions than answers, but after the publication of the main theory of misfortune: an implosion, the need to know more about this phenomenon arised.
A submarine implosion is a phenomenon that occurs when the external pressure of the water is so high that it overcomes the resistance of the structure of the submarine, causing it to deform, break and collapse inwards. This can happen when the sub submerges beyond the limit that it can withstand, which is usually classified data.
An underwater implosion differs from an explosion in that energy is released inward rather than outward. The implosion generates a shock wave that compresses air and water, creating a vacuum bubble that then collapses with great force. The sound of an underwater implosion can be very loud and can be heard from miles away.
Human bodies undergo great compression and deformation when exposed to an underwater implosion, making identification and recovery difficult.
Mythbusters had explained it this way: