1) Get the biggest Dunkin' Donuts coffee they sell.
2) Submerge to a depth of one kilometer in any ocean of your choice and haul it back up.
3) Voilà! Free espresso cup. With salt :(
4) Ask for free refills from clueless teen back onshore.
For reference it's about 111 times the surface pressure or about 3/4 of a ton per square inch.