Solomon Islands WWII Wreck Diving: A Site-by-Site Atlas of Iron Bottom Sound

Iron Bottom Sound has a name that tells you everything. In the six months of the Guadalcanal campaign — August 1942 to February 1943 — so many warships went down in this stretch of water between Guadalcanal, Savo, and the Florida Islands that Allied sailors stopped counting and started calling the seabed what it had become. Solomon Islands WWII wreck diving takes place directly on top of that graveyard, and it is unlike anywhere else on Earth. This is not a museum with a rope line. These are the actual ships and aircraft of one of the Pacific War's turning points, sitting in warm, clear water — some shallow enough for an Open Water diver, some so deep they'll kill you if you try.

This atlas goes wreck by wreck: depths, certification, current, penetration cautions, and the piece of 1942 that makes each one matter. If you want the broad "why the Solomons" pitch — reefs, biodiversity, the whole picture — the Solomon Islands diving guide covers it. This is the iron.

Iron Bottom Sound: What Actually Lies Down There

Diving Iron Bottom Sound is diving on a battlefield. Across those six months, the US and Japanese navies fought at least five major surface engagements here — Savo Island, Cape Esperance, the two nights of the Naval Battle of Guadalcanal, Tassafaronga — plus relentless air raids and transport runs. When the shooting stopped, the Sound held dozens of vessels: cruisers, destroyers, transports, and troopships from both navies, along with a scatter of aircraft shot down or ditched trying to reach Henderson Field.

Here is the honest problem for divers, and the first thing any responsible operator will tell you: most of the famous warships are not recreational dives. The heavy combatants — the cruisers and destroyers that sank in the open Sound — lie in 150 to 1,000-plus metres of water. They belong to technical trimix teams, submersibles, and Ballard-style expeditions, not a diver on a single tank. What you can dive recreationally are the transports and troopships that went down close to shore, plus the aircraft in the shallows. That is still a remarkable roster — it's just worth setting the expectation before you fly halfway around the world imagining you'll finn through the USS Quincy.

The genuinely diveable iron clusters in two places: the beaches west of Honiara on Guadalcanal, and the Western Province around Gizo. We'll take them in that order.

Guadalcanal Wreck Diving: The Bonegi Beaches

Guadalcanal wreck diving is defined by two shore dives about 12 km west of the capital, Honiara, on a black-sand beach at Bonegi. Both are Japanese transports from the November 1942 supply runs — the desperate "Tokyo Express" attempts to reinforce the island — caught and sunk by American aircraft. What makes them special is access: you walk in from the beach. No boat required, though most operators will drive you out and set up the kit. For Honiara-based diving, these two are the backbone of any itinerary.

Bonegi I — Hirokawa Maru

• Depth: roughly 3 m at the shallowest to 55 m at the deepest point
• Certification: Open Water can enjoy the shallow bow; the deep stern is Advanced / Deep-certified territory only
• Current: usually mild, but the site is open to occasional surge and afternoon wind chop on the surface swim-out
• Penetration: possible but silty — for trained wreck divers only

The Hirokawa Maru is a big transport lying on her side down a slope, and the slope is the whole appeal. The bow rises to just a few metres, close enough to the surface that snorkellers see structure, while the hull runs down into technical depths at the stern. You choose your depth. Novices can potter around the shallow bow and superstructure in warm, bright water, thick with soft coral and fish that have colonised eight decades of steel. More experienced divers follow the hull down — but respect the numbers. Fifty-five metres is a decompression dive, not a recreational one, and the deeper you go the more a guide and a plan earn their keep. Buoyancy control is non-negotiable: the slope makes it easy to drift deeper than you meant to, and the interior silts out in a single careless fin-kick.

Bonegi II — Kinugawa Maru

• Depth: roughly 3 m to 25 m
• Certification: Open Water — one of the most accessible wrecks in the Pacific
• Current: mild; the shallowest sections are exposed to surge
• Penetration: limited and low-commitment; not a deep swim-through wreck

Bonegi II, the Kinugawa Maru, is the friendlier of the pair and, for a lot of divers, the more purely enjoyable. She's shallower, and part of the wreck is awash — sections of superstructure break the surface, so you can see her from the beach. That shallow profile makes her a photographer's dream: long bottom times, good light through clear water, coral-crusted steel in the 5-to-15 m range where colour still holds. If your certification tops out at shallow diving, or you're travelling with a snorkelling non-diver, Bonegi II is where you both get a genuine WWII wreck in the same water.

A note on the black sand: these are volcanic beaches, and the fine grey silt gets everywhere and lifts fast. Sort your buoyancy before you reach the hull, not after. The visibility you ruin is your own.

Both Bonegi wrecks are diveable year-round and largely sheltered, which is a big part of why they anchor almost every Solomons itinerary. For how they fit the rest of a trip — logistics, season, what else is nearby — the Solomons destination page lays it out.

Toa Maru Wreck Diving, Gizo: The Best Cargo Wreck in the Pacific

If the Bonegi beaches are the accessible heart of the Sound, the Toa Maru is the crown jewel — and it's worth the hop west to Gizo in the Western Province to reach it. Toa Maru wreck diving is, by a wide margin, the finest cargo-wreck dive in the Solomons and arguably one of the best in the entire Pacific.

• Depth: roughly 10 m to 37 m
• Certification: Advanced Open Water strongly recommended; the best cargo holds sit in the 20-35 m band
• Current: generally mild, sheltered by the surrounding reef and islands
• Penetration: extensive and genuinely rewarding, but silty and overhead — proper wreck training required for the interior

The Toa Maru was a Japanese armed transport, roughly 140 m long, sunk in 1943 while carrying a full cargo of war materiel for the front. She lies on her starboard side on a slope, and what sets her apart isn't the hull — it's what's still inside her. The holds hold the invasion that never landed: a tank, trucks, a motorbike, artillery pieces, ammunition, medical supplies, and crates of sake bottles, still stacked in the dark. Divers regularly report finding intact bottles, gas masks, and vehicle tyres sitting where they've sat since 1943. Swimming into a hold and coming face to face with a tank reorders your personal list of best dives ever.

That said, the interior is a real overhead environment. It's silty, it's dark, and the sheer volume of loose artefacts makes it easy to stir up sediment and lose your reference. The exterior and the upper holds are approachable for a competent Advanced diver with a guide; deep interior penetration is for wreck-certified divers with lights, lines, and the discipline to leave everything where it lies. Take only photos — this is a war grave as much as a dive site, and the artefacts are what make it magic for the next diver too.

Gizo is reachable by a short domestic flight from Honiara, and it's the natural second base of any serious Solomons wreck trip, pairing the iron with the region's reefs and the famous Grand Central Station drift.

Aircraft Wrecks: Zeros, Bombers, and the Mavis

Iron Bottom Sound isn't only ships. The air war over Guadalcanal was ferocious, and the shallows around Honiara and the wider Sound hold a scatter of aircraft — some of the most photogenic and accessible wreck diving in the region.

• Japanese Zeros (A6M): several fighter wrecks lie in shallow, diveable water — often 5-15 m — sitting upright and remarkably intact, easy on gas and certification and a genuine highlight for any diver.
• B-17 Flying Fortress: American heavy bombers went down across the theatre; some sections are within reach of recreational divers, though condition and depth vary site to site.
• The Mavis flying boat: a Kawanishi H6K, one of the more sought-after aircraft wrecks in the Solomons, resting in clear water and large enough to be genuinely impressive underwater.

The appeal of the aircraft is that they scale down beautifully. A Zero in 10 m of water is a full WWII wreck encounter that an Open Water diver — or a snorkeller on a good day — can take in whole. They photograph superbly in the bright shallow light, and they carry the same emotional weight as the ships in a far more comprehensible package: you can read an entire aircraft in one dive.

Depths and exact conditions on the aircraft wrecks vary, and some sites shift with storms and silt over the years. Dive them with a local guide who knows each one's current state — the person who dived it last month knows more than any atlas.

Certification, Safety, and the Remote-Location Reality

The Solomons reward preparation and punish complacency. A few honest points before you book:

• Get your Advanced, and ideally Deep and Wreck, certifications first. So much of the good iron sits below 18 m — the Toa Maru's holds, the Hirokawa Maru's hull — that an Open Water card limits you to a fraction of the experience. On a wreck-focused trip, do the courses at home.
• Penetration is not casual here. Silty interiors, loose artefacts, and overhead environments make wreck penetration an advanced or technical skill. If you're not trained and equipped for overhead diving, admire the holds from the doorway. That isn't a lesser dive — it's a smart one.
• Nitrox is your friend. For repetitive dives in the 25-37 m range, enriched air meaningfully extends bottom time and buys a safety margin. Confirm your operator fills nitrox.
• Evacuation is remote. This is the real cost of the Solomons. The nearest recompression chamber is not around the corner, medical infrastructure is limited, and moving a serious DCS case to definitive care is slow and complicated. Dive conservatively, carry insurance that explicitly covers remote evacuation and hyperbaric treatment, and build in surface intervals you'd think generous elsewhere. This is a place to leave the deco margin on the table.

If you want the numbers side of the trip — flights, boat costs, what a week actually runs — the Solomon Islands liveaboard cost breakdown is honest about it.

Shore, Day-Boat, or Liveaboard?

You can dive the Solomons three ways, and the right answer depends on which iron you're chasing.

For most divers who've come this far, the liveaboard makes the most sense — it stitches the wrecks together with the biodiversity the Solomons are equally famous for, and it reaches sites you simply can't work from shore. The Solomon Islands liveaboard diving guide breaks down the vessels and routes. Just know the fleet here is small, seasons book out, and the wreck-heavy itineraries fill first.

How the Solomons Compare to Truk Lagoon

Every serious wreck diver eventually asks it: Solomons or Truk? They're the two great WWII wreck destinations of the Pacific, and they're genuinely different trips.

Truk (Chuuk) Lagoon is the denser, more concentrated wreck field — dozens of Japanese ships sunk in a single sheltered lagoon during Operation Hailstone, many sitting upright and intact at accessible depths. It's a purpose-built wreck-diving pilgrimage. If your trip is only about wrecks, Truk Lagoon is the more efficient hit of iron.

The Solomons' edge is variety and context. Here the wrecks are woven into world-class reef diving, big-animal action, and the raw historical geography of the Guadalcanal campaign — you dive the actual ground of the battle, then surface onto reefs that stand comparison with Raja Ampat. You come to Truk for the ships. You come to the Solomons for the ships and everything else. Neither is wrong; they answer different questions. If you're still weighing the region against its more famous Coral Triangle neighbour, Solomon Islands vs Raja Ampat takes that head-on.

Planning Your Solomons Wreck Trip

The wreck sites are diveable year-round and largely sheltered, which is a genuine advantage — you're not locked to a narrow window the way you are in some destinations. That said, the reef diving and visibility follow seasonal rhythms worth planning around, so check current departures rather than assuming any week works equally well.

The Solomons are not a casual destination. They ask for solid certification, honest self-assessment about depth and penetration, real insurance, and a tolerance for remoteness. What they give back is the closest thing in diving to time travel — hovering over a tank in the hold of a ship that never delivered it, in warm clear water, with the whole weight of 1942 hanging silent around you. No museum comes close.

When you're ready to turn this atlas into a booked trip, see live departures on the calendar, or tell our concierge what you're after — depth of experience, which wrecks, how much reef versus iron — and we'll match you to the right boat and season. Not sure the Solomons are your destination yet? Put that in the brief too, and we'll tell you honestly.

Related Guides

• Solomon Islands Diving Guide
• Solomon Islands vs Raja Ampat
• Truk Lagoon (Destination)
• Solomon Islands Liveaboard Cost