The Challenger Deep is the
deepest part of the ocean. At 35,813 feet (10,915 meters) it's
almost seven miles below the surface waters. The pressure at
that depth is 16,000 pounds per square inch.
Conversely, the deepest lake in the world is Lake Baikal, in
Siberia, which measures a "mere" 5,370 feet (1637 meters).
If you cut Mount Everest off at sea level and put it on the
ocean bottom in the Challenger Deep, there would still be over
a mile of water over the top of it.