The Royal National Lifeboat Institute (RNLI) worker dropped the sentimental item of jewellery back in 2009 after attending an emergency call-out in Weymouth Harbour, Dorset.
Despite searching the beach with a metal detector and using scuba gear to hunt for the missing band, Mark had no luck finding it and had to resign himself to the fact it was gone for good.
But now, six years on, he's got it back!
Friend Steve Woolford was walking along the quay and remembered the ring, thinking: "You never know, it's worth a look."
And it certainly was, as he spotted the platinum ring - which has a distinctive dent - glinting in the mud!
He exclaimed that he was "over the moon" with his find.
Mark, who has been married since 2004, declared he was "really, really chuffed" to get the ring back. He was quoted in the Daily Mail adding: "I think I owe Steve a bottle of whiskey."
We'd definitely think they should toast the lucky reunion!
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