Marine archaeologist Stuart Bacon and Professor David Sear, of the University of Southampton, will explore the lost city of Dunwich, off the Suffolk coast.
Dunwich gradually disappeared into the sea because of coastal erosion.
"It's about the application of new technology to investigate Britain's Atlantis, then to give this information to the public," Professor Sear said.
Mr Bacon, director of the Suffolk Underwater Studies, first located the debris of the lost city in the 1970s.
"I know the site like the back of my hand because I have dived on it about 1,000 times," said Mr Bacon who has been working on the medieval site since 1971.
"We have found three churches and one chapel."
There is diving evidence of debris from lost chapels and churches but high silt levels in the water means visibility is only a few centimetres.
Mr Sear, professor in physical geography at the University of Southampton, said: "Technical advances have massively improved our ability to create accurate acoustic images of the seafloor."
The expedition will use the latest sonar, underwater camera and scanning equipment to build up a picture of the ancient sunken city, that lies between 10ft (3m) and 50ft (15m) down.
Dunwich was the capital of East Anglia 1,500 years ago.
Its decline began in 1286 when a sea surge hit the East Anglian coast and it was eventually reduced through coastal erosion to the village it is today.
Mr Bacon and Professor Sear hope to begin exploring the seabed in June.
The expedition will cost £25,000 - £20,000 of which has already been raised through a donation from the Esmee Fairbairn Foundation.
Maps and images of the lost city will be exhibited at the Dunwich museum.
A dive of the site will take place later in the year.