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chesthick and shrinking the windows to just two inches in diameter鈥攍ittle more than peepholes。
but it was now strong enough to withstand truly enormous pressures； and in january 1960jacques piccard and lieutenant don walsh of the u。s。 navy sank slowly to the bottom of theocean鈥檚 deepest canyon； the mariana trench； some 250 miles off guam in the western pacific（and discovered； not incidentally； by harry hess with his fathometer）。 it took just under fourhours to fall 35；820 feet； or almost seven miles。 although the pressure at that depth wasnearly 17；000 pounds per square inch； they noticed with surprise that they disturbed a bottom…dwelling flatfish just as they touched down。 they had no facilities for taking photographs； sothere is no visual record of the event。
after just twenty minutes at the world鈥檚 deepest point； they returned to the surface。 it wasthe only occasion on which human beings have gone so deep。
forty years later； the question that naturally occurs is： why has no one gone back since？ tobegin with； further dives were vigorously opposed by vice admiral hyman g。 rickover； aman who had a lively temperament； forceful views； and； most pertinently； control of thedepartmental checkbook。 he thought underwater exploration a waste of resources and pointedout that the navy was not a research institute。 the nation； moreover； was about to beefully preoccupied with space travel and the quest to send a man to the moon； which madedeep sea investigations seem unimportant and rather old…fashioned。 but the decisiveconsideration was that the trieste descent didn鈥檛 actually achieve much。 as a navy officialexplained years later： 鈥渨e didn鈥檛 learn a hell of a lot from it； other than that we could do it。
why do it again？鈥潯t was； in short； a long way to go to find a flatfish； and expensive too。
repeating the exercise today； it has been estimated； would cost at least 100 million。
when underwater researchers realized that the navy had no intention of pursuing apromised exploration program； there was a pained outcry。 partly to placate its critics； thenavy provided funding for a more advanced submersible； to be operated by the woods holeoceanographic institution of massachusetts。 called alvin； in somewhat contracted honor ofthe oceanographer allyn c。 vine； it would be a fully maneuverable minisubmarine； though itwouldn鈥檛 go anywhere near as deep as the trieste。 there was just one problem： the designerscouldn鈥檛 find anyone willing to build it。 according to william j。 broad in the universebelow： 鈥渘o big pany like general dynamics； which made submarines for the navy；wanted to take on a project disparaged by both the bureau of ships and admiral rickover； thegods of naval patronage。鈥潯ventually； not to say improbably； alvin was constructed bygeneral mills； the food pany； at a factory where it made the machines to producebreakfast cereals。
as for what else was down there； people really had very little idea。 well into the 1950s； thebest maps available to oceanographers were overwhelmingly based on a little detail fromscattered surveys going back to 1929 grafted onto； essentially an ocean of guesswork。 the navy had excellent charts with which to guide submarines through canyons and aroundguyots； but it didn鈥檛 wish such information to fall into soviet hands； so it kept its knowledgeclassified。 academics therefore had to make do with sketchy and antiquated surveys or relyon hopeful surmise。 even today our knowledge of the ocean floors remains remarkably lowresolution。 if you look at the moon with a standard backyard telescope you will seesubstantial craters鈥攆racastorious； blancanus； zach； planck； and many others familiar to anylunar scientist鈥攖hat would be unknown if they were on our own ocean floors。 we have bettermaps of mars than we do of our own seabeds。
at the surface level； investigative techniques have also been a trifle ad hoc。 in 1994； thirty…four thousand ice hockey gloves were swept overboard from a korean cargo ship during astorm in the pacific。 the gloves washed up all over； from vancouver to vietnam； helpingoceanographers to trace currents more accurately than they ever had before。
today alvin is nearly forty years old； but it still remains america鈥檚 premier research vessel。
there are still no submersibles that can go anywhere near the depth of the mariana trenchand only five； including alvin； that can reach the depths of the 鈥渁byssal plain鈥濃�攖he deepocean floor鈥攖hat covers more than half the planet鈥檚 surface。 a typical submersible costsabout 25；000 a day to operate； so they are hardly dropped into the water on a whim； still lessput to sea in the hope that they will randomly stumble on something of interest。 it鈥檚 rather asif our firsthand experience of the surface world were based on the work of five guys exploringon garden tractors after dark。 according to robert kunzig； humans may have scrutinized鈥減erhaps a millionth or a billionth of the sea鈥檚 darkness。 maybe less。 maybe much less。鈥�
but oceanographers are nothing if not industrious； and they have made several importantdiscoveries with their limited resources鈥攊ncluding； in 1977； one of the most important andstartling biological discoveries of the twentieth century。 in that year alvin found teemingcolonies of large organisms living on and around deep…sea vents off the gal谩pagos islands鈥攖ube worms over ten feet long； clams a foot wide； shrimps and mussels in profusion；wriggling spaghetti worms。 they all owed their existence to vast colonies of bacteria thatwere deriving their energy and sustenance from hydrogen sulfides鈥攑ounds profoundlytoxic to surface creatures鈥攖hat were pouring steadily from the vents。 it was a worldindependent of sunlight； oxygen； or anything else normally associated with life。 this was aliving system based not on photosynthesis but on chemosynthesis； an arrangement thatbiologists would have dismissed as preposterous had anyone been imaginative enough tosuggest it。
huge amounts of heat and energy flow from these vents。 two dozen of them together willproduce as much energy as a large power station； and the range of temperatures around themis enormous。 the temperature at the p