Boje the seal has travelled a "remarkable" 450 miles from Germany to join the Norfolk population of the mammals at Horsey.
He was spotted on the beach by warden Hannah Yeldham among a group of moulting seals with a yellow tag on his tail flipper.
She searched online and discovered the tag had come from the Seehundstation Seal Centre in Friedrichskoog in Germany.
After contacting the organisation, they responded saying they were delighted to hear the seal they had saved as a pup was doing so well.
The Atlantic grey seal, called Boje (buoy in German) was found severely undernourished on the island of Pellworm off the north German coast in February.
Although he was weaned and estimated to be between five to seven weeks old, he only weighed 14.1 kilos, when he should have weighed nearer 45.
Seal centre staff at Fredrichskoog fed him up and released him on March 3.
A spokesman for the Friends of Horsey Seals said: "So remarkably this seal had swum from northern Germany to Horsey beach in Norfolk, a distance of more than 450 miles in just over six weeks."
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