Thames Estuary
The British Divers Marine Life Rescue says 'Hessy' had come up the river because they were lost or ill.
The highly unusual sight has been confirmed by British Divers Marine Life Rescue.
Figures released by the Zoological Society of London (ZSL) have revealed 138 new harbour and grey seal pups have been born in the Thames Estuary suggesting the once ‘biologically dead’ river is now healthy once again.
No one was injured, Essex Police said.
Police are on the scene.
1,400 tons of live explosives remain on the wreck.