Two Japanese fighter aircraft and a British bomber plane sank in 1944 in Loktak lake in the state of Manipur, home to one of the heaviest but largely unknown battles of the war.
The exact location of the wrecks had been uncertain for decades.
It was recently discovered after a war foundation in the Manipur’s capital Imphal studied official records of the fighting.
“We have been gathering information about the crash from locals and eyewitnesses for about a year. We are ready for the real expedition now,” said the campaign’s co-founder, Yumnam Rajeshwor Singh, on Wednesday.
“We have been doing excavations like this for a long time. It is our passion and hobby.”
The two Japanese planes, known as Oscar, were shot down by British forces on June 17, 1944 but later on the same day, one of their own bomber jets called Wellington crashed too.
A team of 50, led by 10 researchers, will begin excavating “as soon as possible” by going to the middle of the lake that spreads across 285 square kilometres and using GPS and underwater equipment.
Mr Singh said that, according to witness accounts, residents of the area had sold off the planes’ wings, tails and lighter aluminium chunks as scrap metal soon after the crash, leaving behind the heavy parts, including the 600-kilogram engines.
He plans to place the rusty wreckage on display in his foundation’s war museum.
A quiet pocket of British India until then, Manipur was the scene of devastating fighting in the Battle of Imphal from March to July 1944 when the Japanese advanced westward after they captured Burma, backed by a rebel Indian force.
Tens of thousands of soldiers were killed in the fighting, with the Allied victory a major turning point in the Asia campaign that was voted as Britain’s greatest battle by the National Army Museum of London in last year.
In 1942, Japanese forces routed the British in Burma, now Myanmar, which brought them to India’s eastern border from where the attack was launched.
More than 70 years after the end of the war, around 100 British and American aircraft wrecks are believed to be scattered across the jungles of India, Thailand and Malaysia, along with the remains of their crews.