IMAGINE tRYING tO live in a ed by di aste or smell and is so variable in its properties t it is generally benign but at otimes sly lets state, it can scald you or freeze you. In tain organic molecules it can form carbonic acids so nasty t trip trees and eat tatuary. In bulk, ed, it can strike no and. Even for to live , it is anoften murderous substance. e call it er.

    ater is everyo is 80 percent er, a co, a bacterium 75percent. A tomato, at 95 percent, is little but er. Even  er,making us more liquid t to one. ater is strange stuff. It isformless and transparent, and yet o be beside it. It aste and yet aste of it. e ravel great distances and pay small fortunes to see it in suns is dangerous and droens of t  to frolic in it.

    Because er is so ubiquitous end to overlook raordinary substance it is.

    Almost not it can be used to make reliable predictions about ties of oter and based your assumptions on t co it—ably—you  it to boil at minus 135 degrees Fa and to be a gas at roomtemperature.

    Most liquids  by about 10 percent. ater does too, but only doo apoint. Once it is ance of freezing, it begins—perversely, beguilingly,extremely improbably—to expand. By time it is solid, it is almost a tent  expands, ice floats on er—“an utterly bizarreproperty,” according to Jo lacked ttom up. it surface ice to  in,ter’s e a even cing yet more ice.

    Soon even t certainly stay t ime,probably forever—ions to nurture life. ter seemsunary or laws of physics.

    Everyone kno er’s c it consists of onelargisom taco it. tomscling fiercely to t, but also make casual bonds er molecules.

    ture of a er molecule means t it engages in a kind of dance ermolecules, briefly pairing and tners in a quadrille,to use Robert Kunzig’s nice per may not appear terribly lively, but everymolecule in it is cners billions of times a second. t’s ick togeto form bodies like puddles and lakes, but not so tig t be easilyseparated as o a pool of t any given moment only 15percent of tually touching.

    In one sense trong—it is s on a car ermination to beadners. It is also  ttracted more poo to tes a sort of membrane strong enougo support insects andskipping stones. It is ing to a belly flop.

    I  out t   it. Deprived of er, t. itated, to s lengtracts around to prevent blinking.”

    ater is so vital to us t it is easy to overlook t all but t fraction of teron Earto us—deadly poisonous—because of ts .

    e need salt to live, but only in very small amounts, and seaer contains  seventy times more—salt tabolize. A typical liter of seaer ain only about 2.5 teaspoons of common salt—t mucs of ots, compounds, and otively knos. tions of ts and minerals in our tissues isuncannily similar to seaer— and cry seaer, as Margulis and Sagan it—but curiously  tolerate t. take a lot of salt into your body andyour metabolism very quickly goes into crisis. From every cell, er molecules ruseer firemen to try to dilute and carry off take of salt. t of ter to carry out tions. ted. In extreme situations, deion o seizures,unconsciousness, and brain damage. Meanotually become over functioningkidneys you die. t is er.

    ter on Eart is all o get.

    tem is closed: practically speaking, notracted. ter youdrink s job since t least more or less) ac volumes.

    ter realm is kno is over of all ter on Earter part of it in t and is bigger t togetoget over er (51.6 percent to be precise); tlantic  and t, leaving just 3.6 percent to be accounted forby all t a t deeper tlantic and Indian Oceans. Altoget oft’s surface is ocean more tes, ter callour planet not Eart ater.

    Of t of Earter t is fres exists as ice ss. Only tiniestamount—0.036 percent—is found in lakes, rivers, and reservoirs, and an even smaller part—just 0.001 percent—exists in clouds or as vapor. Nearly 90 percent of t’s ice is inAntarctica, and most of t is in Greenland. Go to tanding on nearly t t fifteen feet of it. Antarctica aloneo raise t of t all melted. But if all ter in tmospheoceans would deepen by only an inch.

    Sea level, incidentally, is an almost entirely notional concept. Seas are not level at all.

    tides, s alter er levels considerably from oneocean to anot a foot and a s ern edge—a consequence of trifugal force created by t aser ter tends to flooant tocome er up against ternmargins.

    Considering tance of to us, it is striking  took to take a scientific interest in til o teentury most of  t  ten e and supposition tisuralist Edtlantic and Mediterranean and declared t t all in t. It seemed a reasonable assumption. t at t deptlife, and ter at suco be extreme. So it came assomet transatlantic telegrap o be ted ritus.

    t really organized investigation of t come until 1872, ion betisy, and tis setfortsmouters, netting fiss. It ly dreary  of a complement of 240 scientists and cre mad—“driven to distraction by tine of years of dredging” in torian Samantt 70,000 nautical miles of sea, collected over 4,700 neion to create a fifty-volume report (een years to put togetific discipline:

    oceanograps, t tobe submerged mountains in tlantic, prompting some excited observers to speculatet t continent of Atlantis.

    Because titutional ly ignored t fell to devoted—and veryoccasional—amateurs to tell us er exploration beginsis Barton in 1930. Altners, tten attention. Born in 1877 into a o-do family in Ney, Beebe studied zoology at Columbia University, took ajob as a birdkeeper at ty. tiring of t, o adoptturer and for t quarter century traveled extensively ttractive female assistants ec” or “assistant in fised titles like Edge of table books on hology.

    In trip to ts ofdangling,” as eron, ure. Alts t, it  Barton  of itsconstruction. It iny and necessarily robust c iron 1.5 incaining quartz blocks t only if to become extremely ed. Even by tandards of tecicated. ty—it simply  primitive breatem: to neutralize t out open cans of soda lime, and to absorb moisture tub of calcium cimes o encouragecions.

    But ttle bat ended to do. On t dive, inJune 1930 in ton and Beebe set a o 600 feet. By1934, to 3,028 feet, ay until after ton to a dept, train on every bolt andrivet   any dept  3,000 feet, ttle ported to nineteen tons of pressure persquare inc sucantaneous, as Beebe never failed toobserve in icles, and radio broadcasts. t training to o a metal ball and tons of steel cable,o t, nothem.

    ts didn’t produce  deal of hwhile science.

    Altered many creatures t  been seen before, ts ofvisibility and t t neitrepid aquanauts rained oceanograpten  able to describe tail t real scientistscraved. t carry an external ligt bulb to t ter beloically impenetrable anyo it tz, so anyto vieerested in t. About all t, inconsequence,  t of strange tartled to spy a giant serpent “more ty feet long and very passed too sly to be more tever it  s were generally ignored byacademics.

    After t of 1934, Beebe lost interest in diving and moved on tootures, but Barton persevered. to , Beebe alold anyone on erprise, but Barton seemed unable to step fromtoo, e ts of ter adventures and even starredin a itans of turing a batingand largely fictionalized encounters  squid and tised Camel cigarettes (“t give me jittery nerves”). In 1948 , o 4,500 feet in ttermined to overlook itans of tually t tar of ton is lucky to get a mention.

    At all events,  to be compreeam fromSzerland, Auguste and Jacques Piccard, ”). Cened trieste, after talian city in , tly, t did little more t go up anddos first dives, in early 1954, it descended to belo, nearly times Barton’s record-breaking dive of six years earlier. But deep-sea dives required a greatdeal of costly support, and the Piccards were gradually going broke.

    In 1958, t left trol. No  ttle more than peepholes.

    But it rong enougo and truly enormous pressures, and in January 1960Jacques Piccard and Lieutenant Don also ttom of t canyon, trencern Pacific(and discovered, not incidentally, by er). It took just under fouro fall 35,820 feet, or almost seven miles. Alt t depticed  turbed a bottom-dfis as toucies for taking pograp.

    After just ty minutes at t point, turned to t he only occasion on which human beings have gone so deep.

    Forty years later, tion t naturally occurs is: obegin emperament, forceful vie pertinently, control of tmental c underer exploration a e of resources and pointedout t t a researcitute. tion, moreover,  to becomefully preoccupied ravel and t to send a man to tigations seem unimportant and rat tion  trieste descent didn’t actually acer: “e didn’t learn a  from it, ot .

    again?” It o go to find a flatfisoo.

    Repeating today, it imated,  at least $100 million.

    er researc tention of pursuing apromised exploration program, tcry. Partly to placate its critics, to be operated by titution of Massacts. Called Alvin, in someracted   go anye. t one problem: t find anyone o build it. According to illiam J. Broad in ted to take on a project disparaged by botronage.” Eventually, not to say improbably, Alvin ructed byGeneral Mills, t a factory o producebreakfast cereals.

    As for tle idea. ell into t maps available to oceanograptle detail fromscattered surveys going back to 1929 grafted onto, essentially an ocean of guess cs o guide submarines ts, but it didn’t o fall into Soviet  kept its knoo make do ciquated surveys or relyon oday our knoion. If you look at tandard backyard telescope you antial craters—Fracastorious, Blancanus, Zaco anylunar scientist—t termaps of Mars than we do of our own seabeds.

    At tigative tecrifle ad y-four t overboard from a Korean cargo sorm in to Vietnam, o trace currents more accurately they ever had before.

    today Alvin is nearly forty years old, but it still remains America’s premier research vessel.

    till no submersibles t can go any’s surface. A typical submersible costsabout $25,000 a day to operate, so to ter on a  to sea in t tumble on someterest. It’s ratractors after dark. According to Robert Kunzig, inized“perhe sea’s darkness. Maybe less. Maybe much less.”

    But oceanograp industrious, and tantdiscoveries ed resources—including, in 1977, one of t important andstartling biological discoveries of tietury. In t year Alvin found teemingcolonies of large organisms living on and around deep-sea vents off tube en feet long, clams a foot i ence to vast colonies of bacteria tenance from oxic to surface creatures—t eadily from ts. It  of sunliged em based not on posynt on c tbiologists  it.

    s of  and energy flos. togetation, and temperatures around temperature at t of outfloer may be only three degrees above freezing.

    A type of emperature 140 degrees  its  its tail. Before t  tno complex organisms could survive in er  130 degrees, and  emperatures t and extreme cold to boot. transformed our understanding of ts for life.

    It also ans puzzles of oceanograp many of usdidn’t realize ier ime. At tating t of salt in to bury every bit of land on t to a dept five . Millions of gallons of freser evaporate fromts be to groy t. Sometakes an amount of salt out of terequivalent to t being put in. For t time, no one could figure out his.

    Alvin’s discovery of ts provided ts realized t ts ing mucers in a fisank. As er is taken doo t,salts are stripped from it, and eventually clean er is blo again tacks. t s—it can take up to ten million years to clean an ocean—but itis marvelously efficient as long as you are not in a hurry.

    Pereness from t ternational Geopo study “tivees.” t a secret assignment, you understand, but a proud public boast. In fact,t  mucive es ain appalling vigor, for over a decade. Since 1946, ted Statesy-five-gallon drums of radioactive gunk out to ty miles off t near San Francisco, hemoverboard.

    It e extraordinarily sloppy. Most of tly t you seerusting beations or standing outside factories, ective linings of anytype. o sink, olet er in (and, of course, plutonium, uranium, and strontium out). Before it ed States o aboutfifty ocean sites—almost fifty t tic dumpers were Russia, Cions of Europe.

    And  migtle, ually oundingly, sumptuously, radiantly ignorant of lifebeneat substantial ocean creatures are often remarkably little knoo us—including t mig blue  (to quote David Attenborougs “tongue s  is ts blood vessels are so  you coulds is t gargantuan beast t Eart produced, bigger event cumbrous dinosaurs. Yet tery to us.

    Mucime ance, ores to get t little  entirely fromeavesdropping on t even tery. Blue  up again at t six monter. Sometimes trike up which each already knows.

    remotely understood. And t must routinely cometo to breathe.

    For animals t need never surface, obscurity can be even more tantalizing. Consider t squid. t is a decidedly substantialanimal, railing tentacles t can reacyfeet. It  invertebrate. If you dumped one in a normal be muc no scientist—no person as far as s edcareers to trying to capture, or just glimpse, living giant squid and ly from being  exist in large numbers because tral part of t, and sperm  of feeding.

    1According to one estimate, ty million species of animalsliving in t still undiscovered. t  of  life is in t come until as recently as tion of t captures organisms not just on and near t also buried ints beneatrainental s a deptunder a mile, oods  ted over25,000 creatures—arfising 365 species.

    Even at a deptures representing almost 200species of organism. But ture t oo sloupid toget out of te 1960s a marine biologist named Jo tolo attaco it, and found still more, in particular dense sive eel-like creature, as ing shoals of grenadier fish.

    ance, tom—as many as 390 species of marine creature .

    Interestingly, many of tures o s up to a tant. types as mussels and clams, ravelers. It is no t tain organisms may drift ter until, by some unkno t t a foodopportunity and fall onto it.

    So ax to begin  uniformly bounteous. Altogetenturally productive. Most aquatic species like to be in sers ter to prime tance, constitute  of t are o about 25percent of its fish.

    Elseralia. itline and almost nine million square miles of territorial ers, it ssry, yet, as tim Flannery notes, it doesn’t even make it into topfifty among fisions. Indeed, Australia is a large net importer of seafood. tralia’s ers are, like mucralia itself, essentially desert. (Anotable exception is t Barrier Reef off Queensland,  produces little in trient-rich runoff.

    Even en extremely sensitive to disturbance. In tralia and, to a lesser extent, Nele-kno inental sible parts of giant squid, in particular te in sperm ance kno time you spray on Co reflect t you are dousing yourself in distillate of unseen sea monster.

    rouged in ime at all, fissric tons of rougs madesome alarming discoveries. Rougremely long lived and slouring. Some maybe 150 years old; any rougen may yle because ters ters, some fis once in a lifetime. Clearly tions t cannot stand a great deal of disturbance. Unfortunately, by time tocks ed. Even  it ions recover, if they ever do.

    Elseent.

    Many fis is, slice to terto die. In 1998, s for over $250 a pound. A bookyo for $100. timated in 1994 t tween 40 million and 70 million.

    As of 1995, some 37,000 industrial-sized fis a million smaller boats,aking ty-five yearsearlier. traimes noter planes to locate she air.

    It is estimated t about a quarter of every fis ains “by-catc can’t be landed because too small or of type or caugold t: “e’re still in t drop a netdoy-tric tons of suced fisly in ted, about four pounds of fisures aredestroyed.

    Large areas of traimes a year, a degree of disturbance t no ecosystem can and. At least timates, are being overfislantic tter.  once abounded in suc individual boatscould land ty t in a day. No extinct off t coast of North America.

    Note of cod. In te fifteentury, t found cod in incredible numbers on tern banks of Norter popular tom-feeding fis.

    Georges Banks off Massacts is bigger tate it abuts. till and for centuries to be inexible. Of course t.

    By 1960, tlantic o an estimated 1.6million metric tons. By 1990 to 22,000 metric tons. In commercial terms, tinct. “Fise Mark Kurlansky in ing ory, Cod, “ t tern Atlantic forever. In 1992, cod fisopped altoget as of last autumn, according to a report inNature, stocks  staged a comeback. Kurlansky notes t ts and fisicks  tely byPacific pollock. tes drily, “fisever is left.”

    Muc ine to ers y pounds. Sometimes ty pounds. Left unmolested, lobsters can live for decades—as mucyyears, it is t—and top groers ure. “Biologists,” according to times, “estimate t 90percent of lobsters are cauger t aboutage six.” Despite declining catcinue to receive state andfederal tax incentives t encourage t compel to acquirebigger boats and to  tensively. today fists arereduced to fis market in t, buteven their numbers are now falling.

    e are remarkably ignorant of t rule life in t ougo be in areas t urally impoverisers t to be. tarcticaproduce only about 3 percent of toplankton—far too little, it osupport a complex ecosystem, and yet it does. Crab-eater seals are not a species of animal tmost of us  tually be t numerous large species ofanimal on Earter een million of tarctica. t least op  some works. Remarkably no one knows how.

    All t  t tle about Eart system. But to us, once you start talkingabout life, t deal  kno least  got going in t place.