On October 16, 1968, researchers on board the Lulu, a naval catamaran, lowered the deep-sea submersible Alvin and its three crew members into the Atlantic some 135 miles off the coast of Woods Hole, Massachusetts for what amounted to an underwater whale watch. Then two steel support cables snapped and water poured in through an open hatch. The crew escaped relatively unscathed (Ed Bland, the pilot, sprained his ankle), and the Alvin plunged 4,900 feet down, where it stayed for days and then, on account of rough seas, months.

When the submersible was finally floated again the following year, scientists discovered something unexpected: the crew’s lunch—stainless steel Thermoses with imploded plastic tops, meat-flavored bouillon, apples, bologna sandwiches wrapped in wax paper—were exceptionally well-preserved. Except for discoloration of the bologna and the apples’ pickled appearances, the stuff looked almost as fresh as the day the Alvin accidentally went all the way under. (The authors apparently did a taste test; they said the meat broth was “perfectly palatable.”)

The authors report that after 10 months of deep-sea conditions, the food “exhibited a degree of preservation that, in the case of fruit, equaled that of careful storage and, in the case of starch and proteinaceous materials, appeared to surpass by far that of normal refrigeration.” Was the ocean bottom a kind of desert—a place barren of the vast microbial fauna found flourishing on earth? (Here the authors make an appeal for landfills and caution against dumping garbage into the ocean, where decomposition appeared to have slowed to a near stop.) Or was something else slowing microbial growth?

Four decades later, food scientists are floating the latter idea. Because water exerts a downward pressure—at 5,000 feet down, it’s about 2,200 pounds per square inch, more than enough to rupture your eardrums—the depth of the Alvin’s temporary resting place probably acted as a preservative for the bologna sandwiches. At sea level, this kind of ultra high-pressure processing is used for a variety of foods, including oysters, lobsters, guacamole and fruit juices. In a study published earlier this year, a team of Spanish food scientists juiced strawberries and stored the liquid inside various pressurized chambers. Even at room temperature, they found that high-pressure (hyperbaric) storage slowed the growth of microbes that would otherwise spoil the juice. They suggest that the technology might even prove to be more effective than freezing or refrigerating. And they say the promise of this novel food-processing technology was first demonstrated by the accidental sinking of sandwiches on board the submersible.

Photograph: “Food materials recovered from Alvin after exposure to seawater at a depth of 1540 m for 10 months”/Science, 1971.