Truk Lagoon's Top 5 Most Challenging Dives - Part I

December 14, 2020  •  1 Comment

Truk Lagoon's Top 5 Challenging Dives - Part I

Photos & Text by Mike Gerken

The Dive TeamEri Urmino on left who goes by Umi which means Ocean in Japanese; Keisuke on right and the author center.
The wrecks of Truk Lagoon have something to offer every level of diver. From the newly certified to the advanced technical diver, Truk has it all. However, this list is not about the simpler pleasures that Truk provides. This is about the most challenging dives I have personally encountered in the past 17 years working here as crew, captain and photo-pro on board the M/V Odyssey. Due to the closure of Truk these past 10 months, I have had the opportunity along with fellow Truk dive pros, Keisuke Yokota and Eri Umino, to explore the wrecks in ways we have been unable to in our long careers working here. We were experienced, calculated and methodical in our approach and above all, we came to trust each other’s abilities on the leisurely dives before attempting the more challenging ones. By writing this piece I did not intend to promote or encourage others to attempt these dives on their own. I am simply sharing my explorations and photography with you. I hope you enjoy them.

#5 Reiyo Maru – Lower Engine Room

            Due to severe bomb damage splaying open the wreck, the lower engine room of this merchant vessel is not particularly difficult to enter or exit. It is the max depth of 215’/65M that has secured the Reiyo into the number 5 slot. Depending on your skill set, you may argue that 215’ is not particularly deep but, when your are penetrating in a confined space three levels down with severe silting hazards, the risks increase dramatically. Time is a factor at that depth and you don’t have much of it to deal with a crisis if it should occur.

Reiyo Maru TelegraphOdyssey crew member Dar Hubsch examines the telegraph in the control room at 215'/65.5M. One of the deepest dives in Truk Lagoon.             To date, I have made one dive to the lower engine room with a team of 3 divers in 2019. Two of them were on closed circuit rebreather using trimix while I was on open circuit scuba using air. This depth is about at the edge of where I want to be on open circuit and I aspire to obtain a CCR unit in the future; if for any other reason than to quell the complaints from my CCR buddies about my venting bubbles creating too much silt (which is an undeniable truth). 

            This wreck is seldom visited and the lower engine room even less so. Due to the lack of highlights and extreme depth the Reiyo is not considered a “must-dive” here in Chuuk. With more than 3 dozen wrecks to choose from, she is often overlooked.

Reiyo Maru A massive hole provides a fairly easy entrance into the Reiyo. The upper engine room has much damage.

Bomb Damage

The SkylightsThe open skylights provide a fare amount of ambient light into the upper engine room but most of it dissipates deep inside. The Skylights and air cowling. 


#4 Fumitsuki Destroyer – Engine Room

            Built in 1928, this pre-WWII steam turbine driven destroyer is a rarity in Truk Lagoon if not in the world. It is difficult to determine the functionality of much of the hardware. There are numerous gauge panels, gate valves, voice tubes and main controls complete with a pair of telegraphs to be seen. The photo Fumitsuki engine roomTwin gauge panels in the rear section of engine room. opportunities here are vast but very difficult to achieve. Silting occurs rapidly even with the most well-placed fin kicks. Multiple attempts were made to obtain a mere handful of images.

            Entering the narrow skylight at 120’ into this destroyer’s engine room does not look possible wearing a twin tank configuration so I opted for a single tank. Once inside movements must be made gingerly and contemplatively. There is plenty of machinery and hardware to squeeze past. The “bull in the china shop” approach will lead to possible entrapment and silt-outs. The engine room is by far the most confined space in Truk Lagoon I have dived in. Several fatalities have occurred in here over the years so extreme caution must be used to dive it or simply abstain entirely from entering. Due to the reasonable depth, the engine room of the Fumitsuki lands at number 4. Any deeper and it could have been easily bumped up to the number 1 slot.

Control RoomKeisuke explores the control room complete with telegraphs in the background and these main steam valve controls. The control room.

Voice TubesThis personal discovery came at one of our last dives into the engine room. In the port corner towards the stern were these voice tubes in immaculate condition. A full set of voice tubes.

Control RoomI grabbed this shot of Eri while she was filming the control room. How she managed to get into that spot without silting out the area is a testament to her dive skills. Eri filming in the tight confines of the control room.

Engine Room StuffThe purpose of this tower of valves and gauges is unknown but it is impressive. Engine Room Stuff.

Light BulbThe engine room has many gauge panels such as this one and intact light bulbs.

An intact Light Bulb and gauge panel.


#3  The I-169 Submarine –  Engine Room          

            A crew member of the I-169 failed to close a critical valve when diving to evade air attack. Part of the sub flooded and was unable to re-surface and the crew within all perished. Half of the ship was scuttled by the Japanese command but for reasons unknown the stern section of the vessel remains intact aft of the conning tower.

I-169The Japanese sub, the I-169 in her entirety. To the left is the intact stern and the scuttled bow to the right.

The I-169

            Diving inside the confined remains of a WWII submarine is no easy task. After all, they were not known for their spacious accommodations during the war never mind penetrating a flooded one at 130’/40M wearing a full complement of tech diving gear and carrying a large camera. There is only one other wreck that is more cramped and that is the Fumitsuki.

The Engine Room HatchKeisuke easily navigates through the engine room hatch from astern. This is the easiest of the hatches to penetrate.             Navigating past several tight hatches and hanging machinery requires even more caution as any of the dives in this list. Simply turning around without creating a silt-out is difficult. It is a nightmare for a claustrophobe. In addition, you will want to thoroughly vet your dive buddy before attempting this dive. Dealing with a panicked diver deep inside the sub is a scenario I never want to face. Any crisis encountered must be resolved calmly and quickly on the spot. Egress out of the sub takes at least 3 minutes. We padded this number to allow for complications during our exits. We often had ample time left upon emerging and used it to explore the exterior of this fascinating WWII artifact. The I-169 edged out the Fumitsuki at number 3 due to longer and more complex penetration into the engine room. Any deeper and this dive would be tied for the number 1 spot. Several lives in years past have been lost trying to explore inside the I-169. Some say the ghosts of the crew who perished are to blame for the diver’s demise. The Engine RoomKeisuke and Eri carefully navigate between the two diesel engines.

The Engine Room

Voice TubesKeisuke examines an array of voice tubes with an interesting red paint coating the inside. Possibly antifouling paint.

Voice Tubes

Engine Room HatchA wide angle view of the aft engine room hatch. The Hatch


A Ghostly ShotAnother eerie look at the engine room shooting aft. Ghostly Engine Room

A Tricky ExitKeisuke demonstrates a perfect exit on side mount. The outer hatch, the torpedo loading hatch were photographed through the angled loading hatch. The Exit

The Outer HatchEri is of a smaller size and you can see how tight the hatch is while she exits on side mount. Squeezing through on back mounted twins is tough. The Outer Hatch

The Top 2 most challenging dives to come soon in Part II.


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Sherrail DAMATO(non-registered)
Michael what a great article. I will be back. And I will explore the wrecks in more detail. Can't wait til the next issue. Stay healthy and Merry Christmas.
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