Technically free: a Truk wreck-diving first

Freediving in Truck Lagoon

Freedivers and technical divers team up to take on the wartime wrecks of Truk Lagoon, with KIRK KRACK and JOHN HULLVERSON reporting on what was a unique expedition

Also read: The joys of wreck-diving

There's nothing better than gliding over a reef or wreck, free of tanks and hoses, tied only to the surface by my need for an eventual gulp of air. However, as a former trimix instructor trainer from what seems like a lifetime ago, I have also enjoyed another side of diving, where I stayed at depth for long durations with tanks – sometimes six of them – dangling off me.

Hoses would snake their way around my body as I finned to the rhythmic release of my bubbles, all the while alarms chirping and LEDs flashing my progress towards my eventual surfacing through stages of boredom during decompression.

I‘m not knocking anyone who enjoys this, but I wasn‘t exactly saddened to start giving it all up when the opportunity to follow my life-long curiosity and passion for breath-hold diving or freediving presented itself in 1997. I formed my company Performance Freediving International (PFI) in January of 2000, dedicating myself to “Explore Your Potential Safely Through Education“, which has remained our motto.

Twenty years later I started to look back on that technical/trimix-diving background, to use that education and experience as I developed a new form of freediving, combining it with diver propulsion vehicles in one of the planet’s best wreck-diving playgrounds for a world-first – a freediving expedition to Truk Lagoon.

Wreck Exploration
Truk wreck exploration

Exploring Truk Lagoon

Since becoming a dive instructor in 1988, I had wondered what it would be like to explore Truk Lagoon, in Chuuk State, Micronesia. This graveyard was where dozens of ships and thousands of lives were lost during a horrible turmoil in modern-day history. Five or so years ago, I had tried to put together an expedition to “scooter freedive” Truk, but was met with scepticism regarding the cost and the whole idea of breath-holding on and through wrecks sometimes lying in excess of 60m. 

A “touch-and-go“ freedive to 60m is one thing, but having quality time at depth to meaningfully explore these wrecks is quite another, and requires some creativity and planning.

Our objective was not simply to freedive the wrecks of Truk Lagoon but to explore and capture it with long bottom times from the shallowest to the deepest of the wrecks, to enjoy the exteriors and, limitedly, the insides as well. And, most importantly, to do it safely, with procedures and protocols, back-ups and redundancies. I‘m not one to take risks without first working through the risk analysis – I have a family at home waiting for me.

i HVnFm2G
Using a DPV

With John Hullverson and Chris Bustad, executive and staff instructors at PFI, I joined forces with a good friend who leads the safety rebreather team at our annual Deja Blue training and competition events in the Cayman Islands, Bill Coltart of Pacific Pro Dive.

Bill had been suggesting a combined trip for rebreather tech divers and freedivers for some time. The combination could hardly have been more perfect, so we jumped on the idea and started putting a plan into action – a joint expedition with some of the best technical rebreather divers and freedivers to Truk.

Truk Lagoon was the site of a decisive WW2 battle that took place between US and Japanese forces on 16-17 February, 1944, and left behind it the sunken Ghost Fleet. Code-named Operation Hailstone, the attack was essentially the US version of Pearl Harbour, with American planes sinking an armada of Japanese ships in the atoll’s shallow waters and destroying hundreds of aircraft on the ground and in the air.

Exploring the wrecks of Truk Lagoon
Iconic wreck sights in Truk

All these years later, Truk Lagoon is regarded as the world’s best-preserved battleground wreck-diving site. Scores of ships and planes lie mostly intact and undisturbed in less than 65m feet of water, filled with cargo that includes fighter aircraft, tanks, bulldozers, railroad cars, motorcycles, torpedoes, mines, bombs, boxes of munitions, radios, thousands of various weapons, other artefacts, as well as human remains. The ships also serve as artificial reefs and the amount of sea life on them is astounding.

Tools for the job

Freediving the shallower wrecks would be pretty straightforward. We could simply kick to moderate depths between 20 and 40m, staying there for two to three minutes with perhaps the occasional four-minute freedive if we spent more surface time prepping and used lines to pull down, employing what we call “free immersion”. 

However, in a typical two-minute freedive to 40m, descending and ascending at 1m per second really only leaves you about 40 seconds at depth if you're moderating your workload. Realistically, in the 40m-60m plus zones, this would only allow a touch ‘n’ go, with no time for exploring and filming.

Along with this, a 40m freedive requires a minimum eight-minute surface interval and deeper than that might require a 14-20 minutes. In the course of a day, we would be leaving a lot of the wreck unexplored because our bottom-times would be limited, the number of dives in a day would be small, and exhaustion would take its toll over 10 days. We needed to employ the right tools for the job.

We would be freediving Truk as had never been done before, using scooters, enriched oxygen mixtures and 100% O2 at the surface, employing new surface-interval protocols both for air and accelerated surface intervals when using high-percentage O2 mixtures. This would allow us to get to depth faster and with no effort, explore for longer and enjoy more freedives with less required surface interval.

We could cover the whole wreck in two to three dives, and some in one dive alone, where we could scout and then home in on an area of interest where we might undertake a dozen dives or more.

Scooter freediving

I enjoy scooter freediving. It’s like jumping on a motorbike and going touring rather than lacing up your hiking boots, putting on your backpack and walking through the forest, which is more in line with freediving

For Deja Blue we had been using Dive Xtra‘s Piranha scooters which, weighing less than 16kg, are fast, durable and reliable, while the dry-cell battery allows us to fly with them. Scooters allowed us to provide deep safety to all the competitors on their dives, using a scooter safety freediver to accompany them almost the full length of their dive, down to at least 60m and often deeper.  

In Truk John, Chris and I each had our own scooter, outfitted with both forward and back-facing GoPros, and we would be relying on Suunto D9s and D4s as our main computers and back-ups. This would allow us accurate depth/time, pre-set depth and time alarms for important reminders and surface interval calculations that would be critical in avoiding any DCI issues. 

The scooters would allow us to get to depth at over 2m per second effortlessly, and double our bottom-times. Not only would our functional bottom-times be increased, but the work of getting down and back would be removed, also allowing a more relaxed time to venture around and explore.

This was seen in being able to routinely pull off 3min 30sec-plus average freedive times while working somewhat aggressively filming and exploring. 

However, we always had to remember the most important rule with a scooter: “Never go deeper or stay longer than you couldn’t ditch the scooter and ascend self-powered”. We also had to ensure that we would be ascending where we descended so that our safety divers would be there.

Technical freediving

Freediving in the Wrecks
Diving the Truk wrecks

Technical freediving was our other implementation. This breath-hold diving while also using enriched oxygen mixtures as surface breathing gases helps to flush nitrogen and increase the availability of oxygen to the tissues.

Used both before and/or after a freedive, enriched O2 mixtures (most commonly nitrox 32 or 36 pre-dive and 100% 02 post-dive) can reduce fatigue, decompression stress and surface intervals while both increasing breath-hold times and speeding recovery. 

Conceptualising this idea in the mid-1990s, PFI had been testing these protocols for several years, with our Deja Blue safety freedivers using pre-dive nitrox with great success. A huge advantage was using 80% and higher oxygen mixtures in combination with our new surface-interval protocols, which allowed us to reduce surface intervals by upwards of 40% and fit in more freedives per session with less fatigue at the end of the day. This also removed any decompression stress. 

Ultimately, freedive times averaged around 3min to 3min 45sec, with 2min to 2min 45sec of that being ”bottom time” in the 40-60m range. On one circumnavigation of the Rio De Janeiro Maru, which sat in the 35m range, I did some relaxed scooter sightseeing for a total time of 5min 46sec, while another dive allowed a lazy bottom exploration of 6min 8sec at 31m. On ascending from that one it was difficult to do my surface recovery breathing through the giggles, it had been that much fun.

The wrecks

Over the course of 10 dive days we dived on 17 wrecks, from 3,700-tonne merchant ships like the Nippo Maru to Japanese Zeros and Betty bombers, and even a submarine that still contained the remains of the unfortunate crew. They had perished when their commander, fearing an imminent air attack, ordered the sub to dive before all the hatches had been closed.  

During our dives around and into the holds of these wrecks we saw tanks, trucks, a bulldozer, land-mines, millions of machine-gun bullets, crates of beer-bottles, a whole range of machinery, supplies and personal effects such as medicine-bottles and fine china dinnerware.

And yes, even human remains, which served as a sobering reminder that the wrecks we were enjoying were sunk during a ferociously intense battle that must have seemed like Hell on Earth to the men onboard.  

The Yamagiri
The Yamagiri wreck

Diving procedures

Our dive days began with the captain of our liveaboard briefing us on the particular wreck that we would be diving, followed by a team meeting between the freedivers and rebreather crew to go over the specific dive and safety plans we would be following.  

Next, it was out onto the huge dive-deck to suit up and get our equipment prepared for the dive.  For technical freediving, that included analysing tanks to ensure that we had the correct mix of gases to breathe before and after our dives.  

Our rig consisted of two sturdy Gannet floats supporting a 5m carbon-fibre bar that served as our “home base” in the water. Attached to the bar were mounts for the two tanks – one nitrox for pre-dive breathe-up, and one 02 for post-dive surface recovery. We attached the rig to the mooring buoys, which usually led to the deck or king-posts of the wrecks.

After a suitable warm-up, John, Chris and I took turns exploring the amazing underwater playground. One important note about safety: technical freediving and freediving in overhead environments, such as the interior of sunken wrecks, does require specialised knowledge, training, expertise and planning, and should not be attempted in the absence of any of these factors.

Our typical dive began with an appropriate surface interval followed by a breathe-up and peak inhalation taken directly off the nitrox regulator. The scooters allowed us to get down to the wrecks, usually within about 20 seconds.

From there we followed a predetermined plan of exploration, usually either a tour of the deck, on which sat various equipment such as tanks and anti-aircraft guns, or an exploration of the interior holds and passageways of the ships. They held an amazing variety of cargo from aircraft and aircraft parts to landmines, torpedoes and periscopes.

Using technical freediving and scooters had the intended benefits, and we were excited to be enjoying dives of more than three minutes with complete ease. This was a significant amount of time to observe our surroundings, and the scooters allowed us to cover a lot of territory. It was not uncommon for us to completely circumnavigate these large vessels on a single dive.  

Highlights of the trip

Exploring deep inside the various engine-rooms (always keeping a clear view of the route to the blue water outside) as well as zooming down the outer gangways to explore the whole length of the ship counted among our highlights. It was fascinating viewing the torpedo-holes in the hulls, or the massive bomb-craters in the decks, that had brought these enormous ships to the bottom. 

On our last dive day, we dived the Hoki Maru, a 137m merchant ship resting at 50m. Our protocols had proved their worth and, over the previous 10 days, we had successfully completed what was to our knowledge the first freediving expedition to explore the famous Ghost Fleet of Truk Lagoon.

These wrecks offer a huge variety of options to explore an important part of WW2 naval history.

The liveaboard: Truk Odyssey

Truk Odyssey is a spacious 40m boat equipped with seven staterooms with either king-size or two twin beds, and two private single staterooms. All have ensuite facilities, air-conditioning and DVD player. There is a large dining area and a separate entertainment lounge with TV, VCR, DVD, stereo, library and bar for relaxing after a hard day’s wreck diving.

Out on the dive-deck are personal dive-lockers, rinse-tanks, freshwater shower and warm deck towels. Photographers will find a three-tier camera table and charging station. Transfers from the airport are provided as part of the charter package.

Photographs by Al Hornsby

Also on Divernet: Deeper Into Truk, Rusty Pilgrimage, Rusty Pilgrimage Pt 2


Get a weekly roundup of all Divernet news and articles Scuba Mask
We don’t spam! Read our privacy policy for more info.
Notify of

Inline Feedbacks
View all comments

Connect With Us

Would love your thoughts, please comment.x