Seven-Tenths (14 page)

The reef’s vertical axis is most vividly revealed in terms of light, ranging from the brilliance of sunlight to the inkiest depths. The sea is both lit and heated by the sun’s energy which is absorbed and
scattered from the moment it penetrates the surface. The uppermost metre of the sea effectively absorbs all ultraviolet and infrared, respectively those wavelengths shorter and longer than the visible. Thereafter, seawater absorbs the longer wavelengths first and at about 30 feet down most of the surviving energy is in the blue-green part of the spectrum. From here downwards, increasing numbers of reef creatures are coloured in various shades of red. With almost no visible red light remaining they look dark or black and in still dimmer waters further down become almost invisible. In these top 10 metres the simplest experiments show how much light the water absorbs. Slightly dull objects take on fabulous colours as one swims towards the surface with them. Likewise, a blood-coloured anemone becomes pale and anaemic as one swims away from it.

At a depth of 50 metres only 5 per cent of the sun’s energy still penetrates. If the water is exceedingly clear there is enough light for photosynthesis in plants and algae down to 150 metres. Below that, ordinary plant life cannot exist, which is why there are no great prairies of seaweed covering the deep ocean beds.
*
Generally speaking, the 100-metre mark defines the bottom of the euphotic (‘well lit’) zone, the most productive part of the sea. It was also long believed to mark a theoretical limit for unaided human divers.
The ‘constant weight’ diving record (i.e. with held breath but without fins) is currently 80 metres (105 metres with fins), although the ‘no-limits’ apnea record was broken in 2005 at 209 metres. Such extreme feats are made possible by the mammalian diving reflex, itself highly suggestive of an aquatic past for
Homo
.
*
In splendid violation of a supposed boundary auks (razorbills and guillemots) have sometimes been seen from submersibles at 100 metres while the bird diving record is easily held by the emperor penguin with a recorded 18-minute dive to 265 metres. In any case this 100-metre zone effectively denotes the end of the reef as an ecosystem. Below this its dead corals become a habitat for scattered sponges and, of course, the sundry twilight animal species.

Underwater photography naturally has to take into account this absorption of light energy by water. Even if there is enough ambient light for filming, colour values will be increasingly affected by the progressive filtering out of the warm and comforting wavelengths: first red, then orange, then yellow. ‘Correct’ colour values can be restored by carefully calculated artificial lighting. Any approach to the question of human vision under water leads back to the fact that the narrow waveband in which our eyes operate corresponds very markedly with how sunlight is transmitted in seawater. Quentin Huggett at IOS has wondered whether this setting of our visual ‘window’ reflects our aquatic origin. In air the bandspread is much wider. Several species of insect see at ultraviolet wavelengths, while the pit viper uses infrared sensing to detect warm prey in the dark. Had
Homo
developed differently he might have ‘seen’ a different world.

It is sad that we cannot smell things underwater, though now and then something lodges in a taste bud or receptor to produce the simulacrum of a smell, a pungent impression located somewhere in the muzzle part of the face, neither precisely smell nor taste. Sad,
too, that our hearing is not very acute, and with a limited range from about 16 cycles per second up to 20,000 cycles per second. A mere cat has three times this range, a bat six. The pitch at which human ears are at their most sensitive is that of ‘a child’s or woman’s cry’, according to Yi-fu Tuan, who thinks this suggests that our ear is adapted to favour our species’ survival rather than hunting.
*
This is most aggravating to those reef haunters who have no wish to listen to children and women crying, either above or below water, nor any interest in the survival of their own species, but who would dearly like to eavesdrop among the courthouses, malls, temples, palaces and suburbs of their passion.

My lame experiments sound foolish –
are
foolish to scientists like those aboard
Farnella
who could suggest any amount of gear for increasing my sensing ability. Yet in the early days of submarine warfare the help of people with musical knowledge and perfect pitch was sought in order to classify the sounds made by submerged craft. In World War I the composer and conductor Sir Hamilton Harty was called in by the British Admiralty’s Board for Invention and Research to identify the most likely frequency bands of hull and propeller noises, ‘anticipating by a whole war a similar attempt in America, where the conductor André Kostelanetz was approached for much the same purpose …’.
†
Ernest Rutherford also took a colleague with perfect pitch out in a small boat as part of the war effort. At a prearranged spot, one of the great names in atomic physics took a firm grip of his companion’s ankles while this man stuck his head into the Firth of Forth and listened to the engine note of a British submarine. Hauled back into the dinghy and towelling his head he announced it was a submersible in A flat and he would recognise it anywhere.
‡

Today, with an ultrasound detector I could wiretap the citizens of this submarine city, but it would not be the same. As with medical diagnostic equipment, such apparatus can also blunt other
responses. Ironically, part of the problem of the tropical reef is its very
visibility
. It famously stands as the icon of marine exoticism: brilliant colours, profusion of species, intricacy of shape and design. To make all this more easily seen by means of scuba gear, or more easily heard with ingenious electronics, is somehow too facile to be serious, except for detailed scientific work. Scuba equipment is, of course, indispensible for any work below 40 or 50 feet and down to 200 feet. It is a marvellous invention.
*
However, it has certain disadvantages which are not compatible with travelling alone in remote parts of the world since it is heavy to lug around, expensive to replace when stolen and limited by the local availability of a reliable compressor, to say nothing of the obligatory diving companion. Apart from wishing to be quite alone in the sea, I dislike scuba gear for two additional reasons. It is awkward to wear, all the time making me conscious of itself, of bits of metal and tube, of tanks as bulky as a growth, of belts and dials and rubber straps and harness. But even more importantly, I cannot hear with it. Breaths and bubbles rattle and roar in the ears; the very heart drums in the air hose. It all gets in the way as much as it facilitates, and on most occasions it is preferable to sacrifice depth for the immediacy and greater effort of free diving. The immediacy is whatever transcends discomfort and inconvenience, leaving one uncluttered on borrowed time. By making certain things too easy, scuba equipment gives rise to that curious paradox: the more accessible a thing becomes, the harder it can be to see.
†

Besides, we are not trying to push outwards the frontiers of science, but our own. We are content to have identified the calm room with the big windows letting in the blue-green undersea light and to know that whatever we learn is only a part of what goes on in its corridors and undercrofts and courtyards. It is a consoling pleasure to have hung about this cityscape at night and watched the lights winking to codes unguessed at, to the roar of conversation in a universe off at an angle. It is enough to have clung to the roots of a reef at sunrise and watched the dark gradually bleach from the water. The night shift changes, silence falls. Then the creatures of day emerge and all around the dawn chorus starts, as if invisible behind still-misty water, a great banyan were spreading its branches.

Tourist markets laden with trinkets carry their own charge of melancholy, while seeing the
objets
’ provenance can be brutally sad. People in remote places labour long and hard to live by this trade. The sacks and bundles pile up in bamboo sheds or beneath a covering of dead palm fronds: the shells and corals dragged from the seabed and rotted out in heaps; the hardwood cigarette boxes stacked in piles; the sharks harvested for flesh and teeth, jaws and fins; the alligators stuffed; the baby porcupine fish inflated and lacquered; the aquarium fish poisoned.

Often it seems the more that people become urbanised, the more they want about them talismans of nature on their walls, their shelves, their keyrings. Many souvenirs are marks of pilgrimage, like religious relics, and denote travel. Many of these talismans come from the sea. They are tokens of lineage and are to
Homo
what a family crest is to an aristocrat. The blood line lives on. Yet perversely, this importing from one universe to another, from water to air, is invariably fatal. Nothing looks as dead as a seashell in suburbia, a piece of coral skeleton or a stuffed fish. The otherness of a shark’s tooth, like that of a fossil, begins to ebb the moment it is held in the hand.
Objets trouvés
should be marvelled at, then allowed to become
perdus
at once. Only thus can the transient pleasure of crossed trajectories be sustained in the memory.

The tourist’s trinkets and the traveller’s memorabilia so swiftly decay from prized objects into junk because they are never what they were believed to be. As pieces chipped from nature they have a status oddly close to that of a monument. Just as a monument purports to refer to the past but is always contemporary,
*
so the tourist’s relic
constantly rewrites his version of its origin or the moment he acquired it. The more it tells him of his former self, the more silent it remains about its own past. A shark’s tooth is to the living actuality of the fish which once ate with it as a holiday photograph is to the scene it depicts. A wave washes over us as we hold them but it is not – as we imagine – a wave of cheerful or tearful recall. Such trinkets commemorate a moment not of acquisition but of loss. The tooth, the coral, the hardwood, the fish, were all wrenched from life so we can later discard them as the impedimenta of a previous self. From long experience we know this in advance, remembering the fate of souvenirs from former holidays even as we tell ourselves that this time they are authentic. But the things are already dead when we buy them; and their rattling into the dustbin later is the sound of our own hollow attempt to seize the ever-vanishing present.

In this way, our own deaths prey on the deaths of others. All mementoes immediately turn into species of fossils. The intricate tracery of a coral fan, torn last year from a seabed off Barbados and bleached for export, stands as mutely on a mantelpiece as the ribs of any Carboniferous leaf embossed on a piece of coal. Our psychic recognition that last summer might as well be 90 million years ago robes our trinkets in their characteristic sadness. Acts of memory are incapacitating, trapped as we are between
souvenir
and
memento
mori
. When the objects have collected enough admiration and dust to force this recognition upon us, we throw them away or donate them convulsively to a museum.

But there is no reef after all. The swimmer pursued the dark shadow in
the water, counting his strokes, until he realised it was receding at every
stroke. He gave up and swam in what he hoped was the reverse direction
until now he thinks he has returned to his original position.

Still no boat. It has made no effort to materialise during his brief
absence. Maybe there never was one. Maybe he has been out here in this
radiant deep for days, even weeks? Only the rope’s empty tugging at his
ankle as he swam reminded him of how recently he had been anchored
to his precious craft.

Surely the sun is lower than it was? For the first time he considers
what it will mean to spend the night out here. He is not afraid of the
dark, nor is he afraid of the sea at night. Yet out here the sharks are
maybe not so timorous as they are in the shallower waters near a fringing
reef. They like the freedom of a good depth beneath their bellies.
Since he will be neither kicking nor struggling he has hopes of not
attracting their attention. Like certain predatory humans, they are
beautifully attuned to the sounds of distress. No; he will hang here
quietly, counting the stars or trying to see the lights of land. Perhaps it
will be impossible to resist peering into the Stygian, sparkling gulf he
treads, even though the sight of a great swirl of luminescence turning
suddenly in his direction might well herald his end. No doubt the strike
will be shockingly abrupt, but for some reason he is more frightened by
the thought of a first inquisitive tugging at the painter hanging beneath
him like a bell-pull. He does not want to hear his own terror pealing
out across an empty ocean. At all costs he will be stoical. Fishermen say
shark attacks are painless. One feels great bangings and slammings but
no actual pain.

This is stupid. It is still broad daylight and the boat has only just
gone. There is no possible way in which it could have drifted more than
 
50 or 100
yards. A hundred and fifty at the outside. Well, he will not
wait passively in the water until death in one form or another heaves
up alongside to gulp him down. He will now try to swim a grid pattern.
It will not be easy without any fixable starting point, but
nevertheless he will try.

He heads for the sun, fifty strokes, then turns at what he calculates
to be 90° and swims ten more; then another 90° and back parallel to
his original course. He is pleased to find the surface of the water undulates
more than he had thought. This convinces him that the chances of
happening on the boat are excellent. No sooner has he thought this
than, halfway along the new leg of his search pattern, he spies its prow.
There is no question. No piece of water was ever that shape, black and
slender and curved like a beak. With a cry he abandons the stupid grid
and heads for it. Thank Christ, and about time too.
That
was close.
God, that was close. Never, ever again will he do anything so damned
stupidly careless. …

There is nothing. No prow, no boat, not even a length of floating
timber. Nothing but empty water taking its shape from him. His grid
is broken and lost. He will never find his original position now. He
turns and turns in despair and dejection, incredulous to think he will
not be seen ever again while the bloody boat will probably be wrecked
on some inshore reef to gladden a poor beachcomber looking for useful
spars and panels of marine plywood.