Bloomin' wrecks

The war wrecks of the Coral Seas are among the most beautifully preserved in the world – but not for long. Crispin Long went to see them while they are still in their prime. Photographs by Michael Pitts…

Sixty years ago the idyllic tropical paradise that is the South Pacific was shattered by the cataclysmic events of the Second World War. The damage was enormous – thousands of tonnes of shipping sunk, numerous planes downed, islands decimated and seas polluted. In the face of such destruction, nature’s resilience has been phenomenal. On land, the jungle has grown back, enveloping the debris of war in a thick mantle of green. But it is below the waves where life has really taken advantage of the opportunities opened up by conflict. A whole array of fantastic shipwrecks has been transformed into spectacular living reefs.

When it first sank, all this underwater war wreckage was effectively sterile, but it was only a matter of days before life arrived, brought in by swirling tidal and ocean currents. The sunken ships and planes provided an ideal place for anything that needed to find a home and shelter on something more permanent than the barren, sandy floor of a coral atoll. With the passing of the years, this wreckage of war has turned into fabulous coral reefs, and nowhere more so than the remote Solomon Islands.

The Solomon Islands

The Kasi Maru
This archipelago had spent most of its history in complete obscurity until thrust upon the world stage by the invasion of Japan in 1942. It was the furthest point the Japanese forces reached in their expansion across the Pacific. With the next stop Australia, the Americans counter-attacked at the island of Guadalcanal on 7 August 1942. Successfully establishing a foothold they then started to work their way up the chain of islands of the Solomons, leaving a trail of devastation in their wake.

On Friday 2 July 1943 a Japanese freighter, the Kasi Maru, was busy offloading trucks and fuel in Bairoko Harbour on New Georgia Island. Her luck in avoiding detection was about to run out. Four US Airforce Mitchell B-25 bombers, led by Captain Jean Daugherty were dispatched from Guadalcanal in response to intelligence received that the harbour was being used by the Kasi Maru. At 15.45pm they struck. As the crew was manoeuvring a truck over the side all hell broke loose as the bombers came racing in over the water. The men dived for cover and anti-aircraft batteries opened up, the low-flying B-25s dropping their deadly 500lb bombs. One bomb smashed the Kasi Maru’s hull just forward of amidships with a massive explosion and sent her plunging straight down to the bottom of the sea bed.

Where the Kasi Maru had been moments before, there was now a slick of heavy fuel oil bubbling up to the surface, along with a mass of floating debris. Sticking out of the oil were the ship’s bow mast and gantry amidships – the Kasi had sunk in very shallow water. For the 650 tonne freighter the war was now over. But this wasn’t the end of the Kasi Maru’s story – nature now took a hand. Time, tide and coincidence all conspired to give her a new lease of life. Most of the ships that were sunk during the war had disappeared into the oblivion of the ocean. But for the Kasi Maru, which had sunk in only 14m of water, it was to become the start of a transformation, one which turned the ship into an extraordinary living reef. This was the most perfect place for a wreck to end up.

The wrecked hull’s chance arrival on the sea bed provided just what was needed, a firm fixed base upon which life could anchor. In the clear, warm water of the inlet this life was able to grow fast. The dominant life group were hard corals – the main reef-building organisms, made up of thousands of tiny polyps. But the hard corals must have sunlight, because they rely on algae to provide them with the energy necessary to rapidly build their stony skeletons. Here, at only a few metres’ depth there was plenty of light and the all-important shelter without which the more fragile creatures would become battered to bits in rough weather.

From the moment the wreck sank, there was a deadly battle to attain dominance and establish territory, as she was bombarded with eggs and larvae all trying to gain a foothold. In this contest, branching corals such as staghorns took an early lead. Growing up to 25cm a year, they forged ahead in establishing a commanding presence. The broad horizontal surfaces of the plate corals, although slower to grow, would eventually block out the light from species underneath, allowing them to grow unimpeded. Massive corals such as the brain corals – the toughest of the species – were (and are) the slowest to grow. These are normally found on the exposed side of coral reefs. On the sheltered wreck where storm damage is rare, they had to find room among their more fragile cousins.

Because of this unique combination of conditions the diversity of corals on this wreck numbers more than 100. And, according to scientists from James Cook University in Australia, who recently dived the Kasi Maru, there are even species which are new to science and yet to be officially identified.
Wrecks such as the Kasi Maru are much sought after by researchers – for not only can the growth of the reef be dated to the exact minute, a feat almost impossible on naturally occurring reefs, but also reef zonation and ecology can be clearly determined. The Kasi Maru’s superstructure provides clear, sharp, vertical and horizontal areas of light and shade with both exposed and sheltered surfaces, which in addition to hard corals are colonized by almost every other conceivable type of reef life.

Sponges, clams, soft corals, sea fans and whip corals all jostle for space, their final positions being determined by exposure to current, access to sunlight and food. With the many nooks and crannies found throughout the wreck, more mobile creatures can find hiding places which offer sanctuary, or sites from which to launch ambushes.

And the colonization of the wreck didn’t just stop on the outside of the structure. For down below, a different world exists. This is a coral reef with a hollow heart. Here in a permanently twilight world, where there is no current, the water is crystal-clear and the surfaces have little encrusting growth. An abundance of fish such as cardinalfish and groupers, which normally seek the security of caves on a natural reef, are very much at home here today.

Sunken seaplanes
Throughout the Solomons even the most idyllic looking spots were put to use during the war. The Shortlands in the northern Solomons, one of the quieter and least visited parts of the country, was once a key base for the Japanese to pursue their war aims in the Solomons. It was ideal for their fleet of seaplanes, which at the start of war was the largest in the world, just what was needed to exploit the South Pacific. The numerous lagoons and atolls made for good natural harbours as they did away with the need for permanent airstrips or refuelling facilities. The Shortlands was considered far enough away from the war zone to be safe.

The Allies found the Japanese seaplanes – especially the four-engine Kawanishi flying boats – a real nuisance and in March 1943 they launched an all-out attack on the base. They caught many of the massive flying boats completely unaware, and sank what they could. It was real triumph because the Kawanishis, based on the successful design of the British Sunderland flying boats, had a superior build quality, a long range (up to 4,000 km) and very high payloads. They were widely regarded as the best in their class.

Sinking to the bottom of the channel with varying degrees of damage, they ended up in a totally different environment from the Kasi Maru. Fast-flowing tidal rips and currents rushing through the channel offered different challenges and opportunities for wildlife. Now, out in the middle, at a depth of 18m, the vast wings provide sanctuary for sweetlips, fish that would not normally be found on a sea bed scoured by fast-flowing currents. With the water funnelling through the gap, all the fish have to do is maintain their position to receive the full benefits of oxygenated water passing over their gills, safe from any predator overhead – apart, that is, from local fishermen. Although unvisited by divers for nearly 60 years the Kawanishis can be pinpointed accurately from the surface, such is the harvest of all the succulent marine life.

It wasn’t just large seaplanes that were hit by the American attacks; the single-engine Aichi ‘Jake’ seaplanes were also targeted. In its time the Jake was the mainstay of the Japanese aerial reconnaissance force. It possessed extraordinary endurance, being able to stay aloft for up to 15 hours at a time. Thousands were produced and wherever the Americans could find them, they would try to destroy them. One of the Jakes sits upright in 12m of water and is missing only its propeller, the ends of the wings and its tail she did not suffer as much as the Kawanishis. But with her floats damaged and taking on water, the Jake sank gently down to the sandy bottom of the channel. Although it is in brightly lit, shallow water, there still hasn’t been much hard coral growth on the fuselage, floats and wings. Constant scouring by the current makes it hard for larvae to settle on the wreck and limits successful colonization by coral.


Chuuk Lagoon
The precise location of where a wreck ended up determined its future. How life on each wreck developed was due entirely to its depth, orientation and position in the current. And nowhere is this more obvious than in the wreck-diving Mecca that is Chuuk Lagoon, the greatest concentration of Second World War shipwrecks anywhere.

As the Americans pushed the Japanese out of the Solomons, the war drew closer and closer to their homeland. Chuuk Lagoon was one of the Japanese main forward bases. Many considered it impregnable. Some 1,000 miles to the north of the Solomons, Chuuk was a natural fortress – small islands inside a 40-mile wide lagoon surrounded by reefs. The Americans didn’t relish the consequences of an all-out land attack, relying on air power alone.
On 17 February 1944, wave after wave of fighters and dive-bombers attacked. Having destroyed the Japanese planes, the Americans turned their attention to the now helpless ships. Ship after ship went to the bottom, with more being sunk on this one day than on any other. It was an overwhelming American victory and Chuuk’s reputation lay in ruins.

The sheer size of Chuuk makes the lagoon more like an inland sea. Ships sank in varying depths ranging from a few metres to 60m-plus, all of which determined how they would be colonized by nature. The lagoon’s sandy bottom offered few opportunities for wildlife until the arrival of all these wrecks.

Fujikawa Maru
A torpedo sank the 7,000-tonne freighter Fujikawa Maru; as she sank she managed to remain upright and now sits at a depth of 35m in one of main channels between the islands of the lagoon. At this depth the presence or the lack of light controls colonization. Down in the hold there is little light and no current, and there is very little in the way of life. Chemicals leaking into the water from corroding ammunition make conditions even more inhospitable.
Outside of the wreck, 10m to 15m towards the surface, conditions are much gentler. Above the deck, closer to the surface of the water the slightly increased exposure to the light and the strong current has a dramatic effect. It is still too deep for the majority of hard corals, but there are plenty of other species that can take their place – these soft corals thrive in this deeper water. So critical is position in relation to the glimmer of light and surge of current that any part of the superstructure that places them further out into the water column is massively over-populated. Every square inch is occupied and there is fierce competition for space. Pipe sponges attempt to discourage the growth of other species by secreting toxic chemicals. These soft corals are nothing if not persistent and will quickly exploit any slot that may become vacant; and it seems the sponges will just have to share. The best location of all seems to be the davits from which are coated to so thickly it is hard to recognize them for what they are.

Nippo Maru
The 4,000-tonne freighter, the Nippo Maru, had been diverted from its peacetime duties of delivering bananas, to the role of water-carrier supplying troops on many of the dry outer islands of Chuuk Lagoon. On the 17 February she was one of the first ships to be attacked. Sinking under the impact of three 500lb bombs, she settled upright in 50m of water. With a marked list to port, she is now one of the deeper wrecks in the lagoon.

With much of the life-giving sunlight filtered out, marine life grows much more slowly than on the shallower wrecks and is consequently sparser. Although the pickings may be more meagre than on a shallower wreck, there is still plenty to attract fish including shoals of Moorish idols. They concentrate their reef-gleaning activities on those parts of the wreck closer to the surface and so are more exposed to whatever light filters down to these depths. With her prominent list it is the wreck’s starboard side, which receives more light and current, and it is here that the Moorish idols will be found busily foraging for food.

Bigger fish are also drawn to the ship. Of all the wrecks in Chuuk Lagoon, the Nippo Maru seems to be most popular with grey reef sharks, for reasons that are not yet clear. It could be the promise of food, or the presence of other sharks, or something else. As the hull obstructs the water flow, invisible vortices spin around its superstructure. It could be that the depth and the turbulence make the wreck a focus for the big fish. Sharks like to position themselves in flowing water; it means they can breathe with the minimum of effort. And, as they appear only when the current is running, this could be the reason why they keep returning.

Some creatures have to go wherever the current takes them. Chuuk is noted for its jellyfish swarms. Every now and then a massive congregation of the pulsating bells ends up completely blocking out the view of the superstructure. It is thought the eddies created by swirling water help to hold the jellyfish to the wreck, causing them to bunch up even further. But they will not stay. Soon the current will change and, with no say in the matter, they will continue to wherever next the current takes them, leaving behind the odd individual caught in some piece of awkward wreckage.

Living time-capsules
All these wrecks are now living time-capsules of a momentous point in history. In the normal course of events most of these ships would have ended their lives ignominiously in breakers’ yards converted into scrap. Due to circumstances beyond their control, they have had an unlikely reprieve if not rebirth, becoming fabulous tropical reefs. In fact, their living layer of coral and other encrusting animals have extended their life even further, protecting them from the ravages of time and corrosion. But the years are finally catching up with them, for they are all gradually disappearing. Already the bulkheads are disintegrating, causing the superstructures to collapse in on themselves. In the Solomons, a very seismically active area, every tremor and earthquake shakes the rusting hulks to add to their growing deterioration. In Chuuk Lagoon careless anchoring by some of the larger liveaboard dive boats on the superstructures of the more popular wrecks have hastened the process by pulling over masts and king posts. Within a decade or so the ships as we see them now will have gone leaving just piles of rotting, indistinguishable metal plates.

However, they will leave behind a lasting legacy as the living reefs continue to build on themselves, forming permanent monuments to when war came to the Pacific.