The coral site is located in Arabian Sea, some 100-110 kms of the coastal districts of Ratnagiri and Sindhudurg of Maharashtra.
The place is known as Angria Bank, named after famous Maratha Admiral Kanhoji Angre, who is known to have fought a battle there.
The expedition was initiated to study the biodiversity of the area by the forest department of Maharashtra. Funded by the United Nations Development Fund (UNDP), it was executed by the scientists of NIO in Goa at a cost of Rs 1.5 crore.
"For years we had an inkling that there could corals there. It was only after a project was commissioned by the Maharashtra government that we went under the sea to explore the place," Baban Ingole, chief scientist of Biological Oceanography department of NIO.
On undertaking an expedition, first in January last year, they found a 800 sq km island submerged under the sea, some 100 miles off Vijaydurg fort in Ratnagiri district in Maharashtra.
Of this, only the tip of the island is visible during the low tide.
It was the first expedition where NIO's (RV) Sindhu Sadhna was used.
During the expedition they found some 200 species of flora and fauna. There are 54 species of corals and four of them are soft corals on Angria Bank with different type of fish.
"The peculiarity of Angria Bank corals is that it is in the middle of the sea. Unlike other corals which are either coastal in nature like the Gulf of Mannar or the Andaman and Nicobar corals which are island corals, the Angria Bank is in the middle of the sea.
"It must have been an island some 10,000 years ago, which is now submerged under water. So, while the area around Angria Bank has a depth of 1000 meters, Angria Bank's tip is just 24 feet deep.
"Since it was a hill or a small mountain it was an ideal place for the corals to grow with abundant sunlight and the elevation," Mr Ingole said.
He added that since it is away from the coast, it also saves the corals from pollution emanating from the coast.
The NIO scientists now plan to embark upon another expedition.
"We will undertake another expedition as soon as we get funds," said NIO Director SWA Naqvi said.
NIO scientists said the next phase could be funded by the Ministry of Environment and Forest.
NIO is one of 37 constituent laboratories of the Council of Scientific and Industrial Research (CSIR).
Election Results for Lok Sabha Election 2019 will be out on May 23. Get the latest election news and live updates on ndtv.com/elections. Catch all the action on NDTV Live. Like us on Facebook or follow us on Twitter and Instagram for news updates from each of the 543 parliamentary seats for the election 2019