CNN Erin Burnett OutFront April 9, 2014 23:35:00
Specification says 14,763 feet. but obviously, the ocean at this point could be a little bit deeper than that. it's not fully mapped. so they don't know. i know any change in depth at that far below the surface, it could be an incredible change in pressure. is the bluefin able to operate outside its formal range if it needed to? >> yes. the bluefin standard 21 that phoenix has is rate to 4500 meters. and as you noted, that's about two and a half miles down. at that depth, the pressure is equivalent to having the weight of a cadillac escalade on your thumbnail. it's also slightly above freezing...
Source: archive.org