Notes From Diving
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Posted by John Pohl May 19, 2009 |
Suggestion number two for anyone interested in the marine sciences: learn how to scuba dive. There is nothing so great at building one’s connection (I think) with the sea, as learning the techniques necessary to explore and even work underwater. Being able to observe phenomena and organisms with your own eyes lends context and perspective.
Not to mention, the wonder and awe that comes from roaming about an utterly alien world. It's almost like being an astronaut.
I thought it might be easier to show what I mean rather than simply telling. So I pawed through my dive logs and pulled notes recording a dive that was exactly like what I imagine exploring the moon might be like. Scientifically the dive was unremarkable - except it was a chance to actually disappear beneath the waves for an afternoon, rather than just work with numerical representation of the water column on a computer.
Coworkers using an ROV (Remote Operated Vehicle) to map eel grass beds had gone a little deep in their survey and chanced upon a massive coldwater sponge colongy. Since the location was just a short skiff ride from the lab, several of us joined forces to start a sponge growth study, since that is an area of uncertainty for fisheries managers.
First, however, we had to find the actual colony. Because it was fairly deep as far as non - decompression diving is concerned, we dove using Nitrox, a mixed gas that increases bottom time allowed at (relatively) shallow depths.
I've expanded those notes here using a 3rd party POV.
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The waters around
Their only clue of downward motion is indirect—a pressure change in the ears, the growing shrink-wrap of suits. Otherwise they might be drifting a mere 6 inches below the surface, none the wiser. But at 20 feet the rock flour relents. They bump into the bottom and look around, free once more within a sphere of 2 foot visibility.
They resume the descent, walking on their fingers downward over the silt-dusted shingles of a submerged beach. This is a world of grays and greens:
Granite gray at the surface,
Light green at 20,
Shadowed emerald at 30,
Space black at 40. A hand pressed against a mask can't be seen. For a moment their other senses hold sway, dominated by cold water numbing cheeks, dry air cottoning mouths, the hiss and rattle of mechanized breath--
--then headlamps switch on, lancing out 10 feet in cones of startling white. Plankton and detritus in the water flash with episodic backscatter, like snowflakes round a porch light. The divers are swimming now over a bottom thick with mud. Everything is lunar gray, horizoned with black.
The descent continues to 100 feet, where the slope shelves out. Frigid water slips into gloves and trickles past wrist seals. The vista is a flat plain with zero relief. But there is plenty to catch one's attention, the details magnified by the tension of the moment: the sensation of breathe, resistance against a fin, light flaring over the seabed.
(And always and ever the numbers float with them, invisible yet real, more elusive than fish, changing and dissolving even as they emanate from the diver's lives: the quantification of human life at depth: gas left: 1500 psi. Depth won: 110 feet. Bottom time remaining: 10 minutes, and counting...)
Though their entire search from splash-in to Deco threshold lasts 20 minutes, the divers do not find what they seek. Defeated, they cut loose from the bottom and lazily fin for the surface, rising slower than their bubbles. Light returns, a slow dawning. Just below the billowing rock-flour cap near the surface they check buoyancy and hover, horizontal, for several long relaxing minutes.
Back on the boat, shivering in an October wind, they discuss their return.
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