Initial post-mortem tests show the animals were well fed and healthy
A marine sound expert says he cannot believe that naval activity scared 26 dolphins to their deaths near Falmouth.
The dolphins were found beached around the Percuil river near Falmouth this month in one of the UK's worst mass strandings.
Some local people said the animals could have been scared by naval sonar.
But Ed Harland, who has trained the navy in reducing sonar sound, believes instead that activity in Falmouth docks could have confused the dolphins.
Mr Harland, a freelance consultant on the impact of sound sources on the marine environment, told BBC News: "The military activity in my experience takes place well out in Falmouth Bay."
He added: "To get the animals to swim from five miles offshore into Falmouth Harbour and then divert to a muddy creek is so unlikely that I find it unbelievable."
The Royal Navy admitted it was carrying out training exercises with a submarine and survey ship using sonar in Falmouth Bay.
But Mr Harland believes that the dolphins could have been bow-riding a ship coming into the docks.
He said: "The military is an easy target and their sonars can cause problems.
"But if it was sound that caused the strandings, it must have been closer to the harbour."
He said sound from the docks could confuse dolphins.
"There are many sources of sound around Falmouth.
"Falmouth has a major repair yard for ships that can have faults that can generate a lot of water noise.
"They could have been bow-riding a ship and the sound hitting the rocky sides of the harbour could have been coming at them from all directions.
"They were not sure how to get away and headed towards the tributaries of the Fal river.
"Visibility is low, dolphins rely on sonar and the acoustic environment is so bad that they could have become confused." The dolphins appeared to have been well fed and there were no obvious signs of disease or poisoning, tests showed.
The Natural History Museum is working with vets from the Zoological Society of London in an attempt to discover why the dolphins became stranded.