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Entries in SCUBA (6)


From blue to black - diving in a cenote

If the idea of swimming through narrow stone tunnels with no access to overhead air scares you, then you and I have something in common.  SCUBA is great - the 3D freedom can’t be beaten - but the idea of SCUBA in caves has always carried with it a special kind of terror.  I mean, caving on foot is scary enough, but to do it in a suffocating medium, into the darkness, carrying all your air in a bottle on your back is freaky indeed.  So when the opportunity arose on a recent research trip to Mexico to do a “cavern dive” in a cenote, or sinkhole, I approached the idea with a mix of adolescent excitement and centenarian incontinence.

Luckily, my travelling partners were all experienced divers.  Oh, sorry, I should say Experienced Divers.  Two of them - Marj Awai and Dr. Bruce Carlson - are lifelong SCUBA scientists with thousands of dives in service of ichthyology and aquarium collections.  The other two - Elliott Jessup and Jeff Reid - are dive safety officers and experienced cave divers.  I am comfortable in the water, but admit being a little uncomfortable with my newbie status, especially with respect to diving in caves. Their experience is a source of some comfort. What could go wrong, right? Right??

Purist cavers will note that I earlier said “cavern” dive, which technically is not a cave dive, because if you extinguish artificial light you can always see some natural light to navigate your way back to the opening.  But, let me tell you, having done it, that that is as far underground as I have ever been and it was, in all practical respects a Cave as far as I was concerned; certainly enough so for a first timer.

The particular cenote we dove was Dos Ojos, which is part of the longest mapped cave system yet discovered, incorporating hundreds of kilometers of anastomosing voids in the limestone slab that makes up the eastern Yucatan, not far from Mayan ruins and the town of Tulum.  Most of the system is flooded, meaning that the caves and their spectacular salactite and stalagmite formations formed in dryer times when the sea-level was lower and the caves were full of air, then later the systems filled with water as the sea level rose and freshwater percolated through the stone to fill the voids.  Many cenotes are thus connected by tunnels of water under the stone floor of the jungles of Quintana Roo, and both our dives that day involved descending into one cenote and traveling underground to surface in a second.  Although Dos Ojos itself is very well-known and receives dozens of tourists a day, the same cannot be said of the rest of the cave system.  There are many parts that have yet to be explored, including where the system meets the sea.  That’s right, this flooded freshwater system connects to the ocean, somewhere along the Rivera Maya, maybe somewhere near Xel-Ha. 

Click the map to see the REST of the cave system!

How is it that some parts are a tourist destination and some parts unexplored?  The answer lies in the technical nature of diving these sorts of systems.  What we did was a simple in and out in a very superficial part of the system - we figuratively dipped out toe in the bathtub - but to go to the far reaches of the cave system, especially the uncharted parts, is a huge technical challenge that only a select few experienced divers are able to do.  Such exploratory dives often involve multiple staged dives, with the earlier dives aimed at laying out a guide line to follow on future dives and clipping off SCUBA tanks at regular intervals so that bottom time can be extended and the final push can be a long and penetrating dive that pushes into new territory.

For our much more superficial tourist dive, I was more than happy to be on a single tank and within sight of the blue glow of daylight.  As a diving experience it was, in a word, exquisite.  From the first cooling dip into the water (Q.Roo in August is H.O.T.), to some of the best visibility I’ve seen, to the incredible rock formations and the inquisitive tetras and cave shrimp, it was quite the best dive I have ever done that wasn’t primarily about animals. And as for the terror about being underground and all that noise?  It melted away in the pure joy of the experience.  Nonetheless, it was exciting to think that you could just keep going through tunnel after chamber, for hundreds of kilometers, all underground and underwater and that you could easily discover new rooms and new paths never seen before.  Its a thrill that such opportunities for discovery still exist today; there’s no app for that!


Man vs. Fish - amazing remora video

Most people consider remoras to be no-good hangers-on, sponging off well-meaning marine megafauna. But on one of our research trips to Mexico to study whale sharks this summer, one of the staff divers, Elliott Jessup, had an incredible encounter with one of the most inquisitive fish any of us have ever seen, and scientist/videographer Bruce Carlson caught the whole thing in HD. The waters were full of whale sharks and their attendant remoras, when this little guy took leave of his usual hosts and instead took a real liking to Elliott, even attaching to his butt, and eating his hair.  Learn more about our whale shark research here and you can follow my YouTube channel here and the Georgia Aquarium channel here.

The footage is copyright 2010 Bruce Carlson/Georgia Aquarium and used with permission. 


A photo post from field work in Mexico

Sorry things have been a bit quiet on the blog lately.  Our field work season has reached a crescendo, with several back-to-back trips to Mexico where I and others from Georgia Aquarium are studying whale sharks that aggregate annually in the coastal waters of the Yucatan, and thats left little time for writing.  To learn more about the whale shark project, go here.  Its been a real treat lately, with hundreds of sharks feeding in the area east of Isla Contoy and Isla Mujeres.  Between the boat work, which focuses on photo cataloguing and ecological sampling, and aerial surveys, which focus on counting and distribution, we’ve been gathering a ton of data that will help shed light on why these aggregations form, and how to better protect them in the future.  Rather than write about it, I figured I’d let the pictures do some talking.  Required legalese: all these images are copyright 2010 Alistair Dove/Georgia Aquarium and may not be reproduced without permission.

Flating mats of Sargassum are home to all sorts of things. These baby jacks were seeking shelter from me and caught a red reflection off my rashguardThis is what we came for: a whale shark feeding east of the Yucatan.Any port in a storm: this tiny 2 inch barracuda was hitching a ride with a moon jelly

Most filefish live on rocky and coral reefs, but this one was vigorously defending a little bit of SargassumIts hard not to feel like the whale sharks are checking you out sometimes

Georgia Aquarium senior aquarist Marj Awai wielding the 7D and housing: stills AND HD video *drool*People are the biggest threat to whale sharks. This male had a close encounter with a boat but luckily came away with only shallow scrapes. We see deeper cuts from propellers sometimes, and utmost caution is warranted when moving among the animals.The most common view of a whale shark. Even though they seem to swim effortlessly, keeping up with them is only possible for short distances. This is the last one we’ll see until next years field work season. Adios amigo!


Whats happening all the time in 90% of the oceans, and half the time in the other 10%

To explain the title a little better - most of the oceans are in total darkness all the time, and even the sunlit zone is an inky realm every night when our star visits the other side of the planet.  Accepting that we can't easily visit the bathypelagic zone (the deepest bits) without submersibles or ROV's (remotely operated vehicles), then perhaps the best feel we can get for what's happening in the vast majority of the oceans is to don SCUBA gear and dive the surface of the open ocean, but in the dark.  In preparation for doing a bit of that later this year, I've been looking at "black water night diving" stuff on YouTube.  Honestly, the idea invokes in me a healthy amount of fear, but if these videos are anything to go on, then I hope that will soon be replaced by wonderment and fascination.

Pelagic plankton. I love the flatfish at 0:28. If you know what the spongy looking thing at 1:40 and 4:04 is, please let me know.

Humboldt squids - I especially liked the face-on attack at 2:00 and the strobing at 2:30

I guess this is the most obvious anxiety. The one at 1:20 just gives me the heebie-jeebies!

This video isn't so much pelagic as reef, but the spawning sea cucumbers and then the palolo worms about 5:40 in are just great, and I love the music, which (curiously) is from that abysmal Mel Gibson flick Passion of the Christ.


Gratuitous cenote diving photo post

Doesn't it just make you want to quit your job, grab some gear and catch the first flight to Tulum?  Some of these pics are from commercial operators, but I have never used any of them and endorse none in particular. 

That's it, I'm leaving tomorrow.  Just as soon as I take care of this thing, and some stuff....and that other junk... 


Lazy SCUBA divers - pushing back the frontiers of climate science since 1970

Confused?  Read on...
Australia's CSIRO (the primary government-funded scientific research body; the kool kids say it like SIGH-row) has taken possession of a SCUBA tank last filled by its owner, a Mr. J. Allport, in 1968.  This may represent among the oldest clean compressed air currently available, and the boffins at CSIRO (one such boffin shown below), hope to use the contents to extend the directly-measured CO2 record back a few more years.  This would help improve the quality of climate data just a teensy bit more.  Admit it, that's kinda awesome.

I should call them. I'm pretty sure I've got a ham sandwich from 1982 somewhere in the attic; that must be useful for something...