A post-mortem examination has so far failed to find out why a 36-foot whale died off the Lincolnshire coast.
The 15-ton whale was beached near Sutton Bridge
Rescuers tried in vain to save the sperm whale after it became caught on a sandbank near Sutton Bridge on Sunday.
Volunteers worked for more than a day to try to free the whale, but failed to budge the 15-ton animal and it died at about noon on Monday.
A decision is yet to be made about what will happen to its carcass while clues as to why it beached are sought.
Rescuers from the British Divers Marine Life Rescue Team, based in Uckfield, East Sussex, had resumed efforts to free the animal from a sand bank at Sutton Bridge in The Wash shortly before the 0700 GMT high tide.
"We were not really equipped to lift an animal of that size so it was really a last-ditch attempt," said Alan Knight from the rescue team.
The whale was spotted by a member of the public at about 1000 GMT on Sunday.
Experts have speculated the animal might have become stranded due to ill health, or it could have been confused by the sand banks and shallow water of the The Wash.
Volunteers spent Sunday trying to keep the whale upright so its lungs did not collapse under its own weight.
Inspector John Bowe from the RSPCA was involved in the rescue operation and had been hopeful of a more positive outcome
He said: "All through Sunday the whale stayed stable, its breathing was the same, the vet checked him over, he didn't deteriorate.
"When the tide came in and we saw it thrashing its tail and thrashing around, I really was quite hopeful at that stage."
He added: "It was a deepwater animal and shouldn't be there; it had obviously lost its way."