Christine, 77, was the only person to hear the persistent cries of the two sailors as she tended to her vegetable patch in Looe, Cornwall, on Saturday afternoon.
The two men were half a mile out at sea when Christine heard the cries.
Her garden, which is on a hill around 500 yards from the coast, proved the perfect vantage point and she contacted the coastguard after spotting an upturned dinghy.
One of the men struggling in the water was frantically trying to swim to shore, and had hypothermia. His friend was clinging to the upturned boat and was not wearing a lifejacket.
The men, who were holidaymakers, were rescued from the waves by a lifeboat crew and their boat was towed back to shore.
The lifeguards believe that the men would have died had it not been for Christine's sharp hearing and fast action.
"They were very lucky as I had just got my heading aids," Christine told The Daily Mail. "If it had happened the day before I may not have heard them, and who knows what would have happened."
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