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The Art of Underwater Choreography for EPA Scientific Diving

2012 June 20

by Sean Sheldrake, EPA Region 10 Dive Team and Alan Humphrey, EPA-Environmental Response Team (ERT)

On the mind of the divers, as well as myself, an EPA divemaster, is always safety first and foremost. To be safe and deliver good science in a zero visibility underwater environment, choreography is key. While the divers don’t “dance” underwater very often, they do a dance of sorts with their equipment. Anchorage, current, wind, and other factors impact how the diver will deploy off the back of the vessel. Any misstep in the diver’s descent could cause lines to be crossed or severed, ruining data quality—and worse yet, could become a danger to the diver. EPA divers practice escape from entanglement problems on a regular basis, but underwater choreography ensures these situations are few and far between. Before I let any of my divers hit the water, they all must show me how each hand and fin will be placed as they deploy. We rehearse steps including exhausting air out of their bulky drysuit in preparation for descent, checking their remaining air gauges for their primary and emergency gas supply, and which hand each sampling instrument will be placed in. If lines are crossed during this “dry” drill, we terminate the exercise and start over. If the diver cannot show me how they can complete their task on the vessel, how can they complete it underwater with added distractions? Once the diver shows me how this can be done successfully on land, their 100 pounds plus of specialized diving equipment for contaminated water is donned. I’ll ask them one more time if they are feeling ok and ready to dive as we run through a predive checklist, much like ones pilots use before a flight. Any hesitation and they’ll be asked to step down without penalty from the day’s dives. Once all systems are go for the diver I will check for large vessels in the area and coordinate with the US Coast Guard as needed. We simply will not start a dive near a shipping lane with any possibility of vessels inbound. I tell the diver to “splash” and immediately we go back to the verbal cues we have rehearsed—“Sampler in the left hand, your communications cable in your right…let me know when you feel the bottom on your fin tips—that’s it, keep taking line downcurrent…you’re on target.”

Read more about the latest in EPA scientific diving at

About the authors: Sean Sheldrake and Alan Humphrey both serve on the EPA diving safety board, responsible for setting EPA diving policy requirements. In addition, they both work to share contaminated water diving expertise with first responders and others.

Editor's Note: The opinions expressed here are those of the author. They do not reflect EPA policy, endorsement, or action, and EPA does not verify the accuracy or science of the contents of the blog.

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3 Responses leave one →
  1. Barry Everett permalink*
    June 20, 2012

    Thanks, guys, for this look at the serious business of scientific diving under extremely hazardous conditions.

    As an old 20th century recreational divemaster myself, I can well appreciate and respect the precision with which these divers must perform. An operation like this is as far removed from what I experienced during my clear-water Caribbean diving days, as the Bolshoi is from a sock hop. A ‘dance’ like this starts on land far in advance, with planning, equipment, training, and practice, practice, practice.

    My long ago and far away forays into blue waters evoke fond sun-drenched memories, but my few ventures into cold-water, low/no visibility search and recovery diving, sometimes spawns nightmares, even 40 years later. Thanks for your service.

  2. Elma Sherry permalink
    April 14, 2014

    great too see that activity

  3. permalink
    April 19, 2014

    The art of underwater is really awesome and deep swimming is my favorite.. Thanks for your sharing.

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