Carole Linda Edwards, 51, was diving near the Farne Islands with a Lancashire sub aqua club when she failed to surface on Sunday morning.
Her partner Neil Hyde, 51, unknowingly watched her lifeboat rescue mission as he walked his dog in nearby Seahouses.
Mr Hyde told Champion Newspapers: "She was tragically lost while pursuing her passion for scuba diving."
The body of Ms Edwards, from Westhead, near Ormskirk, was recovered by a diver from another club at 14:30 BST, three-and-a-half hours after she went missing.
Mr Hyde said his partner, who had been a lifeguard at the London Olympics, had "taught hundreds of primary school children to swim".
Ms Edwards had been diving with members of the Phoenix Sub Aqua Club, which is based at the Nye Bevan Pool in Skelmersdale.
A search and rescue helicopter was sent from Prestwick, South Ayrshire, 100 miles (160km) away as part of the search for her.
Despite attempts to revive Ms Edwards by the RNLI, she was confirmed dead shortly afterwards.
Ms Williams lived with her partner, children William, 24 and Rosie, 21 and stepchildren James, 24, and Helena, 22.
Brian Dix, chairman of the Phoenix Sub Aqua Club, said: "She was the most selfless club member we could possibly wish to have.
"She will be impossible to replace and our hearts go out to her family and friends."
A swimming instructor died while "pursuing her passion for scuba diving", her partner has said.