It was supposed to take two hours to reach the Titanic. Last heard from was at one hour forty five. Assuming uniform descent, that would put them at least 9,000 ft down. Plenty pressure there.
Cannot vouch for the accuracy of this article, but if the vessel imploded 1600 ft. from the Titanic, thent it would have been about 10,900 feet below the surface. I would be interested in seeing the energy math using that number as a basis.