The dive community widely regards Chuuk Lagoon (also called Truk Lagoon) as one of the world’s best places for wreck diving. Few places in the world offer such an abundance of wrecks in such a concentrated area. The conditions are near-perfect as well, with year-round warm water, little to no current, and generally good visibility. Many of the wrecks are within recreational depth limits, but some are firmly technical dives. A wreck might be best suited for tech divers for a number of reasons: it might lie deeper than recreational-dive limits; penetration might require skills beyond the basic wreck qualification; or divers may want more bottom time in the 100- to 130-foot (30 to 40 m) range. Although it’s near impossible to choose from the many amazing wrecks, here are our picks for the top five technical dives in Chuuk Lagoon.
The Nippo Maru was a water transport that serviced remote Pacific Islands such as Kwajalein, the Solomon Islands, Rabaul and Truk. It sits on its keel with a list to port, and although it’s within recreational depths, bottom times at 100 to 130 feet (30 to 40 m) are short. A decompression dive will give you a good look in hold No. 1 to see flatbed trucks, a type 95 Ha-Go light tank, and three U.S. howitzers on the main deck. This hold was formerly full of hemispherical beach mines, but locals have removed most of them for dynamite fishing. You can, however, still see boxes of detonators in the bottom of the hold.
Hold No. 2 contains four large water tanks and piles of beer bottles. Moving aft, Hold No. 3 contains some rangefinders, beer bottles, mess kits, gas masks and numerous other small items. The bridge superstructure consists of three deck levels with the navigation bridge on top. The telegraph is still present, along with the telemotor of the helm — a much-sought after shot for photographers. Hold No. 4 shows evidence of damage from one of the 500-pound bombs that sank the ship, and hold no. 5 contains cylindrical foundation supports for large artillery base-mounts.
Decompression dives in the Tec 45/TDI decompression procedures or equivalent range will allow plenty of time to take in the sights over a few dives.
San Francisco Maru
The San Francisco Maru and the Fujikawa Maru are the most famous wrecks in the lagoon. Sitting upright, the deck of the San Francisco starts at 160 feet (50 m) and there is a lot to see. Just as on the Nippo Maru, hold No. 1 formerly contained many hemispherical beach mines, also mostly gone. Hold No. 2 contains two tanker trucks and a staff car, degraded through the years by both the action of the sea, and overly curious divers. Below them are numerous 500-pound bombs, easily identified by their tail fins. You’ll also spot a radial aircraft engine and some shells.
Between hold No. 2 and the main bridge superstructure, three type 95 Ha-Go tanks sit on the deck. Intense fires burned most of the bridge away and what was left has since collapsed. You can, however, see some bathtubs and tiled floors in the officer’s quarters, now exposed on deck.
Aft of hold No. 3 is the engine room, worth an entire dive on its own. It’s both spectacular and easy to enter through the pitched skylights. Hold No. 4 contains two trucks, artillery shells, small-arms ammunition and 55-gallon fuel drums. A tear in the hull is also visible on the port-side. The deck around hold No. 5 has collapsed due to a bomb hit, but inside sit numerous long-lance torpedo bodies, some engines, and more 55-gallon drums.
You must be certified in extended range/trimix to get the most out of this wreck, ideally trimix.
While most divers want to see the San Francisco Maru, the Aikoku Maru is perhaps a more poignant dive given the circumstances around its sinking. It was filled with high-explosive munitions on the morning of Operation Hailstone and, according to eyewitnesses on other ships, as a U.S. Grumman Avenger came in for attack, Japanese anti-aircraft fire hit the plane. It crashed into the forward hold, causing a huge explosion that completely destroyed the entire front half of the ship. A photo taken at this exact moment shows the scale of the explosion — 730 men were killed instantly, based on Japanese sources.
Today, the stern section lies upright in 215 feet (65 m) of water, with the top of the superstructure sitting at 150 feet (45 m). The ship was cut in half at the bridge where the funnel would have stood, but this has now collapsed. A small part of the bridge sits on the starboard side, but the rest of the bridge is missing. Toward the stern, the engine room’s pitched roof allows access, which again could constitute a dive in itself. Moving toward the stern, two 25-mm AA auto cannons are visible, still pointing toward the sky. Hold No. 4 featured accommodation for troops and thus formerly contained the remains of around 400 people, since removed by the Japanese government. However, there are still some remains in the deeper parts of the wreck, so divers must be respectful if they encounter any.
Three levels down in the main superstructure, a galley contains sinks, an oven, china, and water containers. Next door is the mess area, now a large, open space because of the partition degradation. The front half of the ship is worth a dive just to see the large debris field, although because of the devastation, it’s difficult to make out any identifying features.
The Hoki Maru was built in Scotland and originally called the MV Hauraki. The Aikoku Maru captured the ship in the Indian Ocean in 1942 and it was later converted to a naval auxiliary ship under the name Hoki Maru. It now sits upright on the seabed at 160 feet (50 m); the stern will hold the most appeal for divers. The bow section is present, but the explosion of aviation barrels flattened it as the ship was attacked.
The interesting parts of this ship lie in hold No. 4. Dropping in at just over 40m (130ft), you can see aircraft parts including propellers and engines, depth-charges, bombs, long-lance torpedoes, beer bottles, and numerous 55-gallon drums. There are bulldozers, steamrollers, tractors, and trucks that have been heavily damaged by divers over the years but are still nonetheless incredible. A rip in the side of the hull allows access to the hold if you start the dive at the stern on the seabed.
Decompression procedures/Tec 45 will allow you to see most of what this ship has to offer.
Sitting on a slope and leaning heavily to port, the bow of the Amigasan Maru is at 130 feet (40 m) with the stern at 200 feet (60 m). The top of the bridge is at 115 feet (35 m). A 3.7-inch gun sits on a circular platform just aft of the windlasses. Holds No. 1 and 2 are now one large space since the dividing bulkhead is gone. Divers can see numerous 55-gallon drums, along with aircraft wings and propellers. There’s a hole in the hull on the starboard side of hold No. 3 where a torpedo struck. In the tween deck you’ll find a staff car along with some bicycles.
The main superstructure consists of three levels, with the inner rooms now open due to fires that consumed most of the wood used to partition them. The ship’s telegraph and compass are still intact. On the level below, the radio room still contains two large radio sets. At the rear of the superstructure the galley has a large stove, with various pots and pans strewn all over. Moving towards the stern and holds No. 4, 5 and 6, the depth progressively increases. At the stern there is another 3.7-inch gun, and on the port side of the hull there is obvious damage from a bomb or torpedo strike. The Amagisan Maru is very impressive, but divers must have extended range/Tec deep, and trimix is advised.