Ryan Booker
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  • After 5 days my fingerprints have returned sufficiently that Touch ID works about 5% of the time…

    → 7:55 AM, Nov 25
  • The end of a great week of GUE DPV Cave training in Ginnie Springs with Kirill and my teammate Bori. The most fun class I’ve taken in ages.

    Three happy divers in black drysuits after a week of DPV cave diving in Ginnie Strings.
    → 11:21 AM, Nov 18
  • An update, I have one “Ginnie Finger” today. Limestone is grindy. 😬

    We made it to 3700 feet in the Heinkel section of Devil’s in Ginnie today. I think the hardest part was dealing with a bouquet of empty stages and multiple scooters in the Eye for deco.

    One day to go… we dropped everything before the Heinkel and swam through today, but tomorrow we’re taking scooters through.

    → 10:40 AM, Nov 17
  • While I don’t have “Ginnie Fingers”… after a week of diving in High Springs I can no longer use Touch ID to unlock my Mac. 🫵😬

    → 10:59 PM, Nov 13
  • If There's No Map, Have You Really Been There?

    In the last week of our time in Mexico, I took GUE Underwater Cave Survey with Fred Devos (Zero Gravity), and teammate JY—a mix of classroom work, field drills, and real world work continuing the resurvey of Nai Tucha (Tux Kupaxa).

    A hand drawn cave survey map.

    Spending over 10 hours in the same area opens your eyes to how much is really there, how much you usually miss, and how much you will always find, no matter how many times you’ve been there.

    Like taking Cave 1 and 2, Underwater Cave Survey opened my eyes anew.

    A three quarter shot of a man in a grey t-shirt, cargo pants, and a camouflage hat, standing in the jungle and writing in wetnotes using a pencil with a handheld compass attached to it.Making Notes A close up of two men working on a cave survey map.Drawing a Scale Map A close up of underwater survey notes and a halcyon second stage regulator, on top of a set of twin AL80 scuba tanks, overlooking the crystal clear green hued water of a cenote.Underwater Notes

    📸 Photos: Copyright © 2023, Fred Devos.

    → 9:00 AM, Feb 8
  • Una desviación para los tacos

    After Christmas In Austin we braved Southwest Airlines and headed to Mexico—AUS✈️CUN was one of the few flights largely unaffected by the whole mess. Our last trip was late 2019, immediately before… everything.

    Three corn tortilla soft tacos on a white plate. One with chicken and rice, and two pork pastor with corriander, onion and rice.

    The Yucatán Peninsula is a huge limestone karst formed millions of years ago and shaped by everything from ice age and glacial melt to meteor impact1. It’s jungle landscape marked by thousands of cenotes, doorways into another realm, many of them woven into the life and mythology of the Maya.

    Once dry, the cave systems are full of beautiful speleological decorations, the remains of ancient mega fauna, fire pits and artefacts from another lifetime, and sometimes the people that may have inhabited them.

    We spent two weeks diving and exploring this beautiful world.

    I have far too much video to sort though—I’ll post some short clips in the future—perhaps some photos will help explain the draw.

    The first rule of cave diving is to always have a continuous guideline to the open water2.

    A diver hovering among the rocks leading into an underwater cave system, tying a guideline reel to a nearby fallen tree branch, the crystal clear water casting a green blue hue across the scene.Primary Tie-off Two divers descend into the an underwater cave system, their gruideline tied to a nearby fallen tree branch, the crystal clear water casting a green blue hue on the scene.Heading In A Halycon Pathfinder guideline reel securely tied into the main line of an underwater cave system.Tied Into the Mainline

    Once inside, it’s dark, eery, and beautiful. The lights you have with you the only source of illumination.

    A diver swims down a lava tube in an underwater cave system, his dark drysuit and greyscale camouflage fins lit by a team mates primary light, as it illuminates the walls of the cave in greens and blues.Lava Tube A diver swims through dark speleothems and covered in silt an eery green cast illuminating the scene. Speleothems The silouhette of a diver against the brightly lit cave walls and myriad delicate speleothems outlining an underwater cave tunnel.Delicate Speleothems

    One of the most beautiful sites in caves close to the sea is the halocline, an area where the inland fresh water mixes with salt water from the ocean—beautiful and sometimes frustrating when you’re in the rocking chair.

    A diver swimming through a brightly lit white pock marked cave, their hand dragging through the halocline mixing the fresh and salt water layers, trailing a blurry interface behind them.Mixing the Halocline, from Above A completely blurred view of a brightly lit cave tunnel. The halocline so mixed that visibility has dropped to near zero, like looking through a deeply defocused camera lens.In the Middle of the Halocline A diver swimming through a brightly lit white pock marked cave, through the middle of the halocline mixing the fresh and salt water layers, trailing a blurry interface behind them.Mixing the Halocline, from Below

    As always, I’m counting the days until we head back to the Mayan Underworld.


    1. There is a world of information available online about karst geology and hydrogeology. Here’s a good summary of the Yucatan. ↩︎

    2. See Sheck Exley’s foundational book Basic Cave Diving: A Blueprint for Survival. ↩︎

    → 3:01 PM, Feb 5
  • That’s a good looking team.

    → 8:07 PM, Aug 8
  • Striking a pose on the Birchgrove, Sydney, a couple of weeks ago.

    → 1:03 PM, Mar 29
  • I spent the last month or so in Mexico and Florida cave diving.

    One of my team mates, Huw Porter, produced a nice video of some of the highlights, Limestone Rhapsody.

    → 2:01 PM, Nov 15
  • I spent the weekend diving in Tank Cave. I always love these guys.

    → 7:19 PM, Sep 17
  • A couple of snaps of us working at the Battle of Egadi this season.

    → 10:07 PM, Aug 20
  • Interested in diving? Exploration? Adventure? Aged 21–30?

    See where diving can take you, and check out GUE’s NextGen Scholarship

    → 11:04 PM, Jul 18
  • Prepping for another day of exploration… while I pack up ready to head home for the season.

    → 6:47 PM, Jul 13
  • Out of the deep. Lingyu He and I decompressing after some exploration.

    → 2:00 AM, Jul 9
  • Heading to 80m to investigate a Roman ram from 241 BC.

    → 3:15 AM, Jul 5
  • The conditions are just terrible.

    → 6:04 PM, Jul 4
  • We had a great dive this morning. Down to 80m to check an ancient ram that’s been sitting on the sea floor since the battle on 10 March 241 BC.

    → 1:08 AM, Jul 2
  • Home for the next couple of weeks.

    IMG 0337IMG 0969IMG 9164

    → 2:29 AM, Jun 30
  • Today we say ciao Lipari, and head to Favignana.

    → 4:24 PM, Jun 28
  • We had our final dive in Capistello Bay this morning, finishing some survey measurements. Now we’re all packed for Favignana tomorrow.

    → 1:48 AM, Jun 28
  • Beautiful weather and calm seas for a few dives surveying the Capistello Bay wreck. We cleaned up some points and added a couple of ancient Roman anchors to the survey.

    → 4:17 AM, Jun 27
  • Over the last few years, I’ve been part of a marine archaeology project in Sicily, for GUE and the Soprentendenza del Mare.

    While we prepare for this season’s expedition, Chicco, the project lead is opening an exhibition to make the InAccessible accessible.

    Enjoy. I sure do.

    → 10:50 AM, Apr 30
  • Back to Fundamentals: An Introduction to GUE’s Most Popular Diving Course

    → 8:17 PM, Mar 22
  • A quick update from GUE president Jarrod Jablonski, including a great chat with Richard Lundgren regarding our new CCR1 and CCR2 programs.

    → 2:20 AM, Dec 20
  • Recently, GUE released a great new blog for all things diving. Check it out!

    A good place to start is a 20 year retrospective from GUE king pin Jarrod Jablonski.

    → 4:28 PM, Dec 11
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