The San Francisco Maru was to be the dive to which we had been working up all week. Once an inauspicious Japanese freighter, the vessel was built in the early 1900s with a vertical bow, a scooped fantail at her aft end and no raised forecastle.
She would have been considered one of the less important ships to visit Japan’s wartime naval base at Truk Lagoon, in Chu’uk, Micronesia.
However, on a fateful day in February 1944 the US Navy Air Force went on a “turkey shoot” to destroy all merchant vessels lying at anchor awaiting repairs in this Pacific outpost. Of the multitude sunk, the San Francisco Maru is now known at the Million Dollar Wreck.
The reason She was one of the few vessels to remain fully loaded.
The name might describe the value of her military cargo, but others say it’s the value of all the underwater cameras that have been destroyed while diving the wreck. It’s that bit deeper than most of the commonly dived Truk wrecks, deep enough to take inexpensive camera housings beyond their prescribed rating.
We had been breathing nitrox 30 all week, but now nitrox 24 was the gas of choice. Some divers preferred to take a sling tank of nitrox 50 to speed up their decompression. Some went for a smaller pony attached to their main tank, while others opted for a shorter dive and the possibility of a long hang with a single 15-litre.
I took an aluminium 80 (11.33 litres x 200bar) to breathe at depth, with a second of nitrox 30 to switch to as soon as I was back up at 40m.
Computers were set appropriately and the maximum PO2 setting unanimously raised to 1.6 bar to increase their maximum operating depth.
I set my three Suuntos for the gas switch (I like to back up my back-up on trips to faraway places, so that I never have to miss a dive if one fails.)
There was an air of trepidation among those who had never put their computers into deco mode before, but it would be a simple dive if carried out sensibly.

THE SAN FRANCISCO MARU lies with only a slight list to port. Its foremast still stands, the top reaching up to 30m.
As on many of the Truk wrecks, the mast is covered in coral, sponges and other marine growth. We found it full of glassfish being hunted by a persistent band of silvery jacks.
I reasoned that this mast would give me a perfect route back to the surface and be a great place for an entertaining deep stop on the way.
The liveaboard Truk Odyssey was our home for the week. Anchored to a purpose-built mooring ahead of the wreck, her dive platform would pass over the mast of the San Francisco Maru from time to time.
However, Truk Odyssey is very long and, swinging on the wind, her stern described a huge arc. The deco bar was moving quickly, generating its own current effect. This also meant that to plunge straight down from the dive platform could put a diver in danger of missing the wreck altogether, with the prospect of nothing but sand at 63m, so the idea was to swim under our boat to the mooring line and use that as a downline. Most divers stuck to this plan until level with the wreck’s bow.
I cheated. As soon as I could see the mast, I cut the corner and made my way down that instead.
Our two groups of seven had a 15-minute interval between our departures. I was in the vanguard and my cheat put me on the foredeck first. I had the three Japanese battle-tanks to myself for a precious few minutes.
Someone had set up a couple of shell-cases incongruously on the front of one of the tanks. It happens in Truk. Helpful dive-guides are always “displaying” artefacts, and after nearly 40 years they won’t stop now.
The others in my group couldn’t pass the beautiful old bow gun without photographing it. I say “old” because Japanese merchant vessels were equipped with anything available, and this gun was of WW1 vintage.
Two of the tanks had piled up like toys when the ship hit the seabed. The other had slipped back into a corner against a bulkhead. With little marine growth at 53m, they were entirely recognisable.
Soon other photographers arrived, and I ducked into No 2 hold to photograph the remains of a few vehicles stowed in the ’tween decks.
Nearly 70 years of soaking in salt water had left them rather decrepit, unlike the armour-plated tanks, but truck-cabs and water-bowsers crushed by the pressure were visible. Nobody joined me in that hold.
No 1 was too crammed with mines, aerial bombs and munitions to allow me any space, so I went to shoot the big gun.

THE AFT HOLDS WERE filled with ordnance and long Lance torpedoes, but I had no bottom time left to get there. My nitrox 24 was getting low, and it was time to head up the mast for a gas-switch at 40m and a long pause with the jacks near the 30m mark.
I noted the masthead light, still fixed securely amid the dense coral growth.
A lightweight line had been tied to the masthead by a guide escorting the second group, and without having to touch it this provided a good route back to the mooring line.
I waited with the two other British divers at 6m for a few minutes. They had used single-mix 15-litre tanks, so hadn’t been down for quite as long as I had.
When I decided to swim gently at 4m under the swinging hull of the boat, they accelerated past me, reached the deco bar, rigged at the stern, and were climbing the ladders before I even got there. I finished off my 3m stop and joined them back on board.
Of the 13 wrecks we visited that week, this was the deepest, and we dived it only once. The others lay well within range of those using single tanks (albeit including 15-litres) and it was the only dive that anyone might have found daunting simply in terms of depth.
Visibility was around 30m, so one had to keep an eye only on gas-management, deco-stops and the possibility of nitrogen narcosis.

Our ultimate dive in Truk was even more enthralling. Unlike all the other vessels laid waste by Operation Hailstone, the Kansho Maru had sunk without any apparent bomb damage so, exhibiting only the ravages of time, it remains remarkably well-preserved.
It seems she was being pumped out from a presumed serious leak when the attack took place, and that the motor of the massive pump installed in her bilge had been allowed to falter.
She had gradually filled with water before slipping under.
Two of us asked an Odyssey dive guide to give us a tour deep inside the engine-room. I did point out before we left that I was almost twice his height, so might be unable to get through small apertures. He laughed!
The wreck lies in 40m but we were only going to 37m or so. Our guide led us through a skylight, over the massive cylinder heads and down a series of staircases into the bowels of the ship.
I didn’t need gloves, as my hands were full of lamp and large camera rig.
We moved cautiously in the darkness to avoid stirring up the rusty silt, and paused to look at the massive switch gear for the electrical service, and the engineer’s bench with a dozen or so valves still lined up in rows.
Tools hung on the walls in ascending order of size. Even spare parts such as valve springs and bolts with nuts fitted to exactly the same thread position hung there. It must have broken the heart of such a fastidious chief engineer to see all his work slip beneath the surface.

THERE WERE AUXILIARY GENERATORS with controls and gauges, big geared-wheels and various control wheels and levers, along with the engine-room telegraph and the oil-level sight-glasses along the side of the main engine.
Turning to pass down another staircase, I inadvertently leant against a steel panel in the dark. I was dismayed to find it turn to a pile of rusty flakes.
Then it was up and into the galley to see a huge stove complete with cooking utensils and rice-cooker still in place.
Another level up we found the radio-room, where the huge marine radio with massive coils still in place stood erect, among a chaos of debris that had fallen down since the wooden roof of the superstructure rotted away above.

Another wreck with an interesting engine-room is the armed freighter Fujikawa Maru. Again, it’s on even keel at only 34m. All these vessels were merchantmen, hence the Maru suffix, but all carried anti-ship guns and acted as light cruisers as well as transports.
The engine-room has easy access at the upper levels, with a panorama of tools and spares hanging on the bulkheads, and an interesting detour that is the machine workshop, with milling machine and workbench.
Right at the entrance and easy to miss in the darkness is the little air-compressor that has provided iconic Truk wreck-diving images. It’s reminiscent of R2D2 from Star Wars.
Deeper down the stairwells, the engine-room telegraphs can be found on the way to the various generators and a curious wooden telephone box that has stood the test of time. It’s a bit of a squash to get down there, however, especially with twin tanks.
The first of the two forward holds contains machine-guns, ammunition for the bow gun and a simple twin-cylinder long-shaft outboard motor.
The second has the tumbled remains of single-seater fighter planes without engines, thought to be forerunners of the famous Zeke (Zero) fighters.
Under the poop deck is a room with a huge rudder engine and the largest wrench you’ll ever see. It was probably used for taking off the propeller. There are very recognisable guns on both foredeck and stern, and several telegraphs, covered in a riot of sponges that when white-lit appear decorated to a level rarely seen outside a fairground.
It’s the same with the three telegraphs in the pilot-house of the fleet-oiler Shinkoko and the one at the stern. You wouldn’t put their picture on your wall – the colour scheme is too vulgar!
One of the guides showed me around inside the Shinkoko. It was fascinating to see the remains of the communal hot baths so beloved of the Japanese, and to descend deep into the engine-room.

The Nippo Maru has less coral and sponge growth and more algae. Everything is covered in green weed, including four field-guns on the aft part of the deck, and a battle-tank minus gun on the foredeck. There are also anti-aircraft guns that have tumbled from their mountings onto the deck.
Of the 41 ships destroyed in 1944, most burned before sinking. The metal was weakened and marine growth has taken hold much more dramatically than on, say, the Thistlegorm in the Red Sea. In many cases the coral growth is spectacular and some wrecks, such as
the Shinkoko, are almost more interesting as coral reefs, with all their attendant fish life.
The other process that has been going on since Truk Lagoon was first dived is removal of artefacts. Because they are not allowed to be brought up, many have been put on display on some flat part of the hull or in the holds.
It’s an odd practice, but does give divers the chance to see smaller items they might otherwise have missed. Elsewhere, they would have disappeared altogether.
The forward holds of the Sankisan Maru, for instance, are full of rifle ammunition, their wooden boxes long since rotted away. Many bands of ammo have been pulled out and exhibited on the cross-bars of the ’tween decks, and some machine-guns surreally decorate
a ventilation shaft.
The vehicles in the second forward hold were obviously too heavy to move, but are rotting away.
The forecastle is splashed with colour, mainly due to nature, although the cans of paint it contained were littered about when it struck the seabed.

A DISPLAY ON THE DESTROYER Fumizuki includes a book. As each book dissolves following divers’ careless fin-kicks, another mysteriously replaces it a few days later.
The Fumizuki is one of the few true warships in the lagoon. Admiral Koga (Yamamoto’s successor) got wind of the US attack and managed to evacuate nearly all his fighting ships, but this one was under repair without engines.
One engine was hastily assembled from cannibalised parts and the captain attempted to get away, but the vessel was unseaworthy and he was too late.
That Fumizuki was subject to savage and repeated attacks is evident.
Likewise the Hoki Maru – the heavily assaulted forward section is barely recognisable as a ship, and is encapsulated in colourful corals and sponges, while the aft section makes for a fantastic photo-shoot, with one hold packed with construction equipment, including a bulldozer and several trucks.
On the other hand, the remaining hold contains drums of aviation fuel, some of which has leaked and pooled inside the wreck under the ’tween decks.
This can cause nasty burns to unsuspecting divers, including anyone swimming above when the exhaled bubbles of a diver in the hold displace any fuel, which then drifts upwards.

Two passenger liners lie on their sides and are regularly visited by leisure-divers. The Heian Maru is probably the largest wreck in Truk. She carried long Lance torpedoes in her holds, but I had to slip through quite a narrow slot to find them.
Piles of submarine periscopes lie along companionways on upper decks, indicating that the vessel was used as a submarine tender and supply ship.
The holds are mainly empty, but bookcases and cabinets have tumbled down to the lower reaches of the wreck, and drawers full of ink-bottles have been located. The long propshafts and huge propellers are a sight to behold.
The Rio de Janeiro Maru was also probably used as a submarine tender.
Its holds are wide open, and the most interesting aspects of the remaining cargo are the wooden crates of beer-bottles stacked around the propshaft tunnel in the aftmost hold, and the huge gun-turret gearing rings, probably intended for coastal defences, seen elsewhere.
The twin props of this forlorn giant have become another iconic image of Truk Lagoon’s wrecks.
Two armed freighters served as auxiliary cruisers, and both of these lie on their port sides.
The Kiyuzumi Maru went down without her guns, presumably taken off for use as coastal defence. The holds are empty, but a large lathe has tumbled through the rotting metal, and the remains of a crewman’s bicycle still dangles on a wall.
The twin-barrelled anti-aircraft guns are decayed but recognisable on the bridge wings.
A similar vessel, the Yamagiri Maru, had discharged her cargo, but the spacious engine-room makes a good introduction to such places. One hold still contains what’s left of big battleship gun-shells.
Gas masks made of incongruous blue rubber are littered on all the wrecks.

After a week of concentrated diving on 13 of Truk’s most accessible wrecks, I felt I had only skimmed the surface. The wrecks are now deteriorating fast, and some are becoming fragile.
Many will soon become simply magnificent coral reefs. There is a wealth of diving to experience if you lust after rust. Buy now while stocks last.

The US Operation Hailstone was always seen as retribution for the Japanese attack at Pearl Harbour.
Truk Lagoon (part of Chu’uk) was the centre for naval operations of the Japanese empire in its self-proclaimed Asian Economic Co-operation Zone. It had become a Japanese possession under a mandate from the League of Nations after the German surrender in 1918, and was considered the most formidable of all the Japanese strongholds.
Truk is actually 11 volcanic islands, scattered about this 40-mile-wide lagoon. It served as the anchorage for the combined Japanese Imperial fleets. The occupiers had years in which to build the infrastructure necessary, and even had time to remodel one decoy island to resemble an aircraft-carrier from the air.
They got wind of the attack when they sighted a US reconnaissance aircraft, and managed to evacuate most military assets, but the loss of such a huge fleet of support vessels was a major blow to the Japanese in this theatre of war.
Afterwards, the Americans simply bypassed the islands and left the garrison to starve. Truk’s destroyed military facilities played no further part in the Japanese war effort. We should treat these wrecks with respect, because they are war graves.
GETTING THERE: Fly via Guam from Manila. (Guam is a US territory and a pre-obtained ESTA is required.)
DIVING & ACCOMMODATION:Truk Odyssey is a large and comfortable liveaboard that moors directly over the sites. You can dive from shore-based centres or another permanently moored liveaboard, but this involves long rides in small boats.
WHEN TO GO: Any time. Truk is 7° north of the Equator and the lagoon is sheltered.
SPECIAL EQUIPMENT: Back-up computers recommended, and broad-beam lights for viewing in dark, confined spaces. Full-length wetsuits with hoods and gloves will protect skin softened by repeated immersion from damage through inadvertent contact with rusty metal in the dark interiors. Wreck reels were in evidence but never deployed.
HEALTH: The nearest hyperbaric facilities are in Guam, so long safety stops are recommended. No malaria is in evidence.
PRICES: Scuba Safaris offers trips from £3435pp, including flights, transfers; day room in Guam; two nights room-only at the Blue Lagoon Resort (after the boat trip); seven nights on Truk Odyssey all-inclusive except farewell dinner; six days’ unlimited diving and free nitrox.