HomeMilitaryDeep-Sea Survey & Forensic Discovery: The 2017 USS Indianapolis (CA-35) Wreck Site

Deep-Sea Survey & Forensic Discovery: The 2017 USS Indianapolis (CA-35) Wreck Site

Military

In August 2017, a deep-sea research expedition led by Paul G. Allen aboard the R/V Petrel discovered the long-lost wreckage of the Portland-class heavy cruiser USS Indianapolis (CA-35). Resting 5,500 meters (~18,000 feet / 3.4 miles) beneath the surface of the Philippine Sea, the warship had been missing since its catastrophic sinking on July 30, 1945.

After delivering critical atomic bomb components (enriched uranium-235 for “Little Boy”) to Tinian Island, the cruiser was struck by two Type 95 torpedoes launched by the Imperial Japanese Navy submarine I-58. The vessel sank in just 12 minutes, leaving roughly 900 survivors in open ocean waters subject to severe exposure, dehydration, and the most lethal shark feeding frenzy in recorded naval history before rescue four days later.

The high-definition Remotely Operated Vehicle (ROV) and sonar surveys conducted by R/V Petrel revealed exceptional structural preservation in the cold, hypoxic abyssal waters, confirming impact mechanics, weapons status, and wreckage distribution.

1. Tactical Incident & Wreckage Summary

The image shows that the ship remains largely intact thanks to the depth of its location, the lack of oxygen, and the cold temperatures
The image shows that the ship remains largely intact thanks to the depth of its location, the lack of oxygen, and the cold temperatures
  • Date of Loss: July 30, 1945 (~00:15 Local Time)
  • Discovery Date: August 18, 2017
  • Location: Philippine Sea (Confidential coordinates; within the Guam–Philippines transit corridor)
  • Depth: ~5,500 meters (18,000 ft / 3.4 miles) | Partially silt-imbedded (~20 ft into seafloor sediment)
  • Vessel Class: Portland-class Heavy Cruiser (Hull Designation: CA-35)
  • Attacking Unit: Imperial Japanese Navy Submarine I-58 (Commander Mochitsura Hashimoto)
  • Ordnance Impacted: 2 × Type 95 Oxygen Torpedoes (1,200 lb warheads, 48-knot velocity)
  • Casualties: 1,197 Total Crew | ~300 Lost with Ship | 317 Final Survivors (880 Total Fatalities)
  • Research Vessel: R/V Petrel (Paul G. Allen Marine Operations / Vulcan Inc.)
  • Legal / Memorial Status: Protected U.S. Navy Sunken Military Craft & Official War Memorial

2. Sequence of Events & Forensic ROV Survey Findings

The USS Indianapolis was a ship that was built for its plethora of guns. The crew was also able to glimpse the 5-inch AFT gun, which fired a 50-pound shell about seven miles
The USS Indianapolis was a ship that was built for its plethora of guns. The crew was also able to glimpse the 5-inch AFT gun, which fired a 50-pound shell about seven miles
[Atom Bomb Component Delivery (Tinian)] ──► [Transit to Leyte, Philippines] ──► [I-58 Torpedo Strike (00:15)] ──► [12-Minute Capsize & Sinking] ──► [4-Day Survivor Drift & Shark Attacks] ──► [2017 R/V Petrel ROV Mapping]
  • Target Positioning & Torpedo Strike: Re-analysis of historical naval landing craft logs that logged a sighting of Indianapolis shortly before the attack allowed the Petrel team to refine search grids. ROV footage confirmed structural damage near the forward barbette corresponding to two 1,200 lb torpedo warhead detonations, which severed forward communications, electrical power, and structural integrity.
  • Rapid Hull Separation & Debris Mapping: Sonar mapping showed a broad debris field oriented along a westward vector, confirming the cruiser’s heading and speed (~17 knots) at impact. Heavy structures—including the bridge, main 8-inch barbettes, and aircraft cranes—detached as the ship capsized during its 3.4-mile descent.
  • Scout Aircraft & Hangar Field: The survey identified intact wreckage from two Curtiss SC-1 Seahawk floatplanes inside and adjacent to the ship’s hangar area. The aircraft retained visible US Navy insignia panels, wing structures, and pilot emergency medical kits.
  • Armament Preservation: ROV imagery documented 40mm Bofors anti-aircraft mounts with live brass shell casings still loaded in the feed ramps, 5-inch/25-caliber dual-purpose guns, and the hull number “35” painted on the superstructure—providing definitive visual identification.

3. Structural & Environmental Profile

Allen said that the discovery was a humbling experience and a means of honoring sailors he saw as playing a vital role in ending World War Two
Allen said that the discovery was a humbling experience and a means of honoring sailors he saw as playing a vital role in ending World War Two
ParameterTechnical Details
Displacement / Dimensions:9,800 tons (standard) / 9,950 tons (full load) | Length: 610 ft (186 m)
Environmental Conditions:~2°C seawater, extreme hydrostatic pressure (~530 atm), near-zero dissolved oxygen
Preservation Highlights:Captain Charles B. McVay III’s cabin doorway intact; forward deck preserved; hull “35” marking legible; “Victory Tally” score markings preserved on bridge structure
Armament Status:Forward 8-inch/55 caliber gun barbettes damaged by torpedo pressure wave; starboard 40mm anti-aircraft batteries in “locked and loaded” battery position
Site Management:Coordinates held strictly confidential by the U.S. Navy and the Paul G. Allen Estate under the Sunken Military Craft Act
The image of the Indianapolis is seen with the use of sonar, which enables researchers to map out the debris field
The image of the Indianapolis is seen with the use of sonar, which enables researchers to map out the debris field
Deep sea explorers used a drone which was sent to the ocean floor in order to beam back stunning images of the USS Indianapolis
Deep sea explorers used a drone which was sent to the ocean floor in order to beam back stunning images of the USS Indianapolis
The USS Indianapolis is a naval gunship that lies three miles beneath the surface of the Philippine Sea after it was sunk by a Japanese torpedo during World War II
The USS Indianapolis is a naval gunship that lies three miles beneath the surface of the Philippine Sea after it was sunk by a Japanese torpedo during World War II
The 'victory tally' is seen above. It was meant to symbolize the number of Japanese ships and aircraft that were downed
The ‘victory tally’ is seen above. It was meant to symbolize the number of Japanese ships and aircraft that were downed
The expedition was also able to get an up-close look at a .40m anti-aircraft Starboard gun
The expedition was also able to get an up-close look at a .40m anti-aircraft Starboard gun
The shells that are still locked and loaded into the gun are visible
The shells that are still locked and loaded into the gun are visible
The stunning images also showed the debris field surrounding the Indianapolis. The above image shows part of an aircraft
The stunning images also showed the debris field surrounding the Indianapolis. The above image shows part of an aircraft
The aircraft hangar, where the ship stored the scout planes that were used for reconnaissance, is seen in the above image
The aircraft hangar, where the ship stored the scout planes that were used for reconnaissance, is seen in the above image
When the expedition first caught a glimpse of the number '35' as seen above, it was confirmation that the vessel was the Indianapolis
When the expedition first caught a glimpse of the number ’35’ as seen above, it was confirmation that the vessel was the Indianapolis
The U.S. Navy and Paul Allen's expedition team have agreed to keep the exact location of the vessel confidential
The U.S. Navy and Paul Allen’s expedition team have agreed to keep the exact location of the vessel confidential
The USS Indianapolis is now effectively an underwater grave and a war memorial to the lives lost
The USS Indianapolis is now effectively an underwater grave and a war memorial to the lives lost
The scientists were able to discover that 20 feet of the Indianapolis was buried in the mud at the bottom of the ocean between Guam and the Philippines
The scientists were able to discover that 20 feet of the Indianapolis was buried in the mud at the bottom of the ocean between Guam and the Philippines
Portions of the warship remain preserved, including part of the forward deck. The researchers operating the drone use remote control to get the lay of the land from the bow to the stern of the ship
Portions of the warship remain preserved, including part of the forward deck. The researchers operating the drone use remote control to get the lay of the land from the bow to the stern of the ship
The image near the barbette shows a doorway that leads into the cabin of the captain of the Indianapolis, Charles Butler McVay III

The image near the barbette shows a doorway that leads into the cabin of the captain of the Indianapolis, Charles Butler McVay III

Another image beamed back from the drone shows the barbette, the gun emplacement used by a warship
Another image beamed back from the drone shows the barbette, the gun emplacement used by a warship
The above image shows the hull of the ship, which is largely intact though the signs of damage caused by one of the torpedoes are apparent
The above image shows the hull of the ship, which is largely intact though the signs of damage caused by one of the torpedoes are apparent
The researchers also find the remnants of two SC-1 SeaHawk scout planes - which were used largely for reconnaissance - that were held in the ship's aircraft hangar
The researchers also find the remnants of two SC-1 SeaHawk scout planes – which were used largely for reconnaissance – that were held in the ship’s aircraft hangar
The USS Indianapolis cruiser was returning from its mission to deliver components for the atomic bomb that would soon be dropped on the Japanese city of Hiroshima when it was fired upon in the North Pacific Ocean by a Japanese submarine on July 30, 1945
The USS Indianapolis cruiser was returning from its mission to deliver components for the atomic bomb that would soon be dropped on the Japanese city of Hiroshima when it was fired upon in the North Pacific Ocean by a Japanese submarine on July 30, 1945