Last Updated on September 26, 2023

A team led by Ocean Exploration Trust aboard Exploration Vessel (E/V) Nautilus conducted in-depth archaeological assessments in September 2023 of three World War II aircraft carriers lost during the epic Battle of Midway. The assessments include the first visual survey of Imperial Japanese Navy (IJN) Akagi, the first detailed views of the USS Yorktown since it was first located 25 years ago, and a comprehensive survey of Japan’s IJN Kaga.

These historically significant wrecks were explored in their final resting places within Papahānaumokuākea Marine National Monument (PMNM), the largest protected area in the U.S. and one of the largest in the world. This UNESCO World Heritage site is distinguished for both its cultural and natural significance. It is currently being considered for national marine sanctuary designation to further safeguard its diverse natural, cultural, and maritime heritage resources for generations to come.

“This expedition is not only rewriting history and our understanding of these special places, but also pushing the limits of what we thought was possible in terms of interdisciplinary collaboration,” Daniel Wagner, Ph.D., Chief Scientist for Ocean Exploration Trust, said. “During over 43 hours at depth, we methodically circumnavigated these historic wrecks, bringing to light many features in great detail, including their armament, battle, and sinking-related damage. Many anti-aircraft guns were still pointing up, providing clues about the final moments on these iconic ships.”

USS Yorktown shipwreck
USS Yorktown shipwreck. Credit: Ocean Exploration Trust, NOAA.

The surveys were aimed at documenting these historically-significant wrecks, examining their condition, and honoring all those who lost their lives on both sides of this battle that turned the tide of the war in the Pacific.

The expedition team completed non-invasive visual surveys of the wrecks during three excursions below 5,100 meters (more than 16,600 feet and 2,770 fathoms), representing the deepest of the more than 1,000 remotely operated vehicle dives conducted off E/V Nautilus to date.

“To explore Papahānaumokuākea Marine National Monument and these iconic naval ships is a solemn privilege on many levels,” Rick Spinrad, Ph.D., NOAA Administrator, said. “NOAA is grateful to the Monument Trustees, our partners, and the Nautilus expedition team who have made it possible to venture to these extreme depths and share these discoveries with the world.”

Throughout the mission, video surveys were streamed live via, allowing the public and those with personal connections to the Battle of Midway an opportunity to explore and honor this unique history and engage with the onboard expedition team.

Archaeologists from Japan, the U.S., and over 100 experts worldwide were able to connect to ship operations via telepresence technology, helping guide the mission and providing valuable real-time interpretations throughout the surveys. 

Each dive was launched and closed with protocol ceremonies to honor this sacred place and all who lost their lives in ways that reflected their significance to Kānaka ʻOiwi (Native Hawaiian), Japanese, and U.S. military families and communities.

“On this occasion, we meet on those same Pacific waters in which Japan and the U.S. once met in battle, but this time as allies and fellow researchers,” Kosei Nomura, Minister, Head of Economic Section, Embassy of Japan, said. “We are reminded that today’s peace and tomorrow’s discoveries are built on the sacrifices of war, and so in my view, it is meaningful that Japan and the U.S. are now deepening their cooperation at Midway, utilizing such cutting-edge technology.”

This is the first time since the vessel went down in 1942 that anyone has seen the Japanese aircraft carrier IJN Akagi, which was initially located during a mapping survey conducted by Vulcan, Incorporated in 2019 involving U.S. Navy participation. The E/V Nautilus team spent 14 hours surveying Akagi, examining battle and seafloor collision damage in the ship’s structure.

“An important part of our mission here at the Naval History and Heritage Command is to locate, interpret, and protect lost U.S. Navy ships and aircraft, particularly those that represent the last resting place of American sailors,” Samuel Cox, Director of the Naval History and Heritage Command, said.  “We’re incredibly grateful for collaborative relationships – such as that with the Ocean Exploration Trust and NOAA’s Office of Ocean Exploration on this expedition – which enable us to document and assess the condition of these important war graves of both American and Japanese sailors.”

The expedition’s survey of USS Yorktown was the first time the world could witness this site in real-time, 25 years after it was initially located during a joint U.S. Navy and National Geographic Society expedition led by Robert Ballard, PhD., president and founder of Ocean Exploration Trust.  The team also conducted the first in-depth archaeological survey of Kaga that will yield data in the public domain.

“The vast majority of our ocean lies in very deep waters that we know virtually nothing about,” Wagner, chief scientist for Ocean Exploration Trust, said.  “These deep-sea explorations highlight how many extraordinary things are still hidden and waiting to be found in the great depths of our ocean.”

About the Battle of Midway

The June 1942 Battle of Midway was a pivotal naval battle between the U.S. and Japan that changed the course of World War II in the Pacific. Ahead of the battle, an intelligence breakthrough allowed U.S. forces to advance on invading Japanese carrier task forces at Midway Atoll, 1,000 miles northwest of Honolulu.

The four-day battle claimed the lives of over 3,400 U.S. and Japanese service members, and saw the loss of over 390 aircraft and seven major ships including IJN aircraft carriers Akagi, Kaga, Sōryū, Hiryū, and USS Yorktown.   

About Each Shipwreck

IJN Akagi 赤城

IJN Akagi shipwreck.
IJN Akagi shipwreck. Credit: Ocean Exploration Trust, NOAA

Built in the 1920s and retrofitted with a large flight deck to become an aircraft carrier ahead of WWII, the 260-meter (855-foot) Akagi (赤城, “red castle”) sailed with a crew complement of 1,600 servicemen.

During the Battle of Midway, Akagi was struck by multiple aerial bombs and engulfed in flames. Before sunrise on June 5, as fires continued to burn aboard, Japanese destroyers scuttled the ship to prevent its capture, sinking it bow first.

In 2019, a team from Vulcan Inc. and the U.S. Navy using autonomous underwater vehicle mapping surveys located a target preliminarily identified as the Imperial Japanese Navy aircraft carrier Akagi from sonar images. However, the carrier was not investigated at that time.

IJN Kaga 加賀

Built in the 1920s and retrofitted with a flight deck to accommodate heavier aircraft ahead of WWII, the 247-meter (812-foot) aircraft carrier Kaga (加賀, “Increased joy,” named for the former Kaga Province in present-day Ishikawa Prefecture/ SW Japan) sailed with a crew complement of 1,708 servicemen.  

During the Battle of Midway, Kaga was struck by multiple aerial bombs and engulfed in flames from the hangar deck. On June 4, a Japanese destroyer scuttled the ship to prevent its capture, sinking it stern first.

In 1999, a joint expedition between Nauticos Corporation and the U.S. Naval Oceanographic Office located a large piece of wreckage, identified as part of the upper hangar deck of Kaga.

Later, in 2019, after a comprehensive exploration campaign using high-resolution acoustic mapping tools, a team from Vulcan Incorporated discovered the substantial remains of the Japanese carrier Kaga lying over 5,400 meters beneath the waves and was able to complete a partial archaeological survey of the site.

USS Yorktown

Commissioned in 1937, the 267.7-meter (809.6-foot) aircraft carrier USS Yorktown (CV-5) sailed with a complement of over 2,000 servicemen. 

During the Battle of Midway, Yorktown was attacked in two waves and struck with multiple bombs and torpedoes.  Despite multi-day efforts to save the ship and take it under tow, the Yorktown was ultimately torpedoed by a Japanese submarine and sank on June 7, 1942.

USS Yorktown was discovered in 1998 on a joint U.S. Navy and National Geographic Society expedition led by Robert Ballard, Ph.D., founder and president of Ocean Exploration Trust. The mission located the ship using a tethered vehicle but was not able to complete a thorough archaeological survey of the site at that time.