There is just something about 8,000 tons per square inch of pressure

 

On January 23rd, 1960, the bathysphere Trieste dove to the deepest part of any ocean on the face of the Earth.  The Mariana Trench. near Guam is 35,797 feet deep.  Auguste Picard and USN Lt. Don Walsh dove to the bottom in the Trieste on that day more than 52 years ago.  The only way to see outside of the craft was through a small, but very thick, tapered block of plexiglass--which at the time was the only clear material that could withstand the tremendous pressure of almost seven miles of water pressing down on it.  Only one problem.  It cracked when the Trieste was about 9/10ths of the way down.  The entire vessel shuddered.  They continued but ended up spending a truncated twenty minutes on the bottom--no doubt warily eying the window the whole time.  

 

Well, James Cameron, known more for making blockbusters like the Titanic than for making history, became the third person, and the only solo diver, to reach the bottom of the earth.  And guess what?  The laws of physics have not changed in the past five decades.  His vessel cracked, also.  This time it sprung a leak of hydraulic fluid.  It cut his time on the bottom short, too.