A New York City bomb squad's commanding officer has described a total containment vessel as "an inside-out diving vessel." Whereas a diving vessel protects a diver by keeping the immense pressure of the ocean out, a total containment vessel keeps outsiders safe by keeping the enormous pressure of an exploding bomb safe within its chamber. The chamber contains tiny vents that allow air pressure to escape harmlessly, while containing the force of the bomb and all its shrapnel.