Imperial Japanese Navy (IJN) Akagi was a Japanese aircraft carrier that was in service from 1927 to 1942. Originally it was constructed as an Amagi-Class battlecruiser, but construction was halted in 1922 with the signing of the Washington Naval Treaty. The incomplete hull of Akagi was thus taken and used to build a larger and faster aircraft carrier in 1927.
Akagi had an overall length of 261 meters, a beam of 31 meters, a draft of 8 meters, a maximum speed of 31.5 knots, and a range of 12,000 miles at 16 knots. It had a complement of 1630 personnel and 88 aircraft.
Akagi was Japan’s flagship for the Kidō Butai or “Mobile Force” during the Pacific Theatre. It took part in several operations during World War II (WWII) to include the attack on Pearl Harbor on December 7, 1941, the invasion of Rabaul on January 20, 1942, the Indian Ocean Raid from March 31 to April 10, 1942, and the Battle of Midway from June 4-7, 1942. During the Battle of Midway, three Douglas SBD Dauntlesses from the USS Enterprise targeted Akagi including one piloted by Lieutenant Commander Dick Best who struck Akagi with a 1000 lb bomb at the middle elevator for the upper hangar deck causing a chain of explosions. Akagi soon became inoperable and on June 5, 1942, Admiral Yamamoto ordered the carrier to be scuttled. Destroyers Arashi, Hagikaze, Maikaze, and Nowaki each fired torpedoes into Akagi, sinking the carrier.
On September 10, 2023, Ocean Exploration Trust and partners surveyed Akagi during the Ala ‘Aumoana Kai Uli expedition, which was funded by NOAA Ocean Exploration via the Ocean Exploration Cooperative Institute. At the time, Akagi was intact, but severely disarticulated, and embedded in seafloor sediment. A large section aft of amidships was damaged, likely caused from bomb damage and a subsequent chain of explosions. The deck on the starboard side slopes downward, indicative of where the exhaust port would have been.
18 hours of video was collected of Akagi using remotely operated vehicle Atalanta. The video was processed into still images and color corrected using Adobe Photoshop 2024. 9,097 images were used to create 17 photo models of the site. These included 5 models that captured portions of the starboard side, 2 models that captured portions of the port side, 3 that captured portions of the deck structures, 3 models that captured portions of the stern, 1 model of the bow, and 3 models of the debris field along the port side of the site. Due to some of the models being distorted and having quality issues, only 10 photo models were aligned using Rhinoceros 8.
A link to the full annotated video of this dive on SeaTube will be posted here when available.
Site Name: IJN Akagi
Type: UCH
UCH Vessel Date Built: March 25, 1927
UCH Vessel Date Sank: June 5, 1942
Hull Material: Steel
Official Number: N/A
Expedition Number: NA154
Expedition Name: Ala ‘Aumoana Kai Uli
ROV Dive Number: T1002
ROV Dive Date: September 10, 2023
Location: Hawai‘i
Depth: 5 kilometers
Length: 261.21 meters
Width: 31 meters
ROV Used: Atalanta
Camera Information: Insite Mini-Zeus HD
Video or Stills: Video
Number of Images Used/Format: 9,097/JPG
Image Alignment Percentage: 86%
Number of Tie Points: 1,152,584
Link to Raw Video Footage: Link to come
Time to Complete: 64 hours
Orthomosaic Views Available: No
Images Available: Yes
Animations Available: Yes
Available File Exports/Location/POC: archaeology.oceanexploration@noaa.gov
Link to NOAA Ocean Exploration Project Page: https://oceanexplorer.noaa.gov/news/oer-updates/2023/midway.html
Software: Agisoft Metashape Professional Version 2.1.0, Rhinoceros 8
Developer: Raymond Phipps, NOAA Ocean Exploration explorer-in-training, April 26, 2024.
Credit: Model courtesy of NOAA Ocean Exploration, Ala ‘Aumoana Kai Uli expedition.
