The former Beatle, 67, spent an energetic day on the beach doing yoga and playing in the sea, showing off an impressive physique for a man of his age.
He appears to be in much better shape than in the final days of his marriage to Heather Mills.
Me and my girls: Paul McCartney plays with Nancy Shevell and his six-year-old daughter Beatrice
Love me do: Sir Paul leans in for a kiss from Nancy
He also seems to be taking more care of his appearance, hence the impressive hairdo which seems a little longer, thicker and darker than before.
There is obviously a healthy influence in his life - but whether it is girlfriend Nancy Shevell or his daughter Beatrice, six, is unclear.
Both are with him on holiday.
While Beatrice took shelter from the midday sun after a romp in the water, Sir Paul and the svelte Miss Shevell, 48, practised their stretches.
The pair have officially been an item for 20 months.
The Mail understands that Sir Paul gathered his family in the Caribbean over the New Year to ease them into the idea that he is planning a more permanent future with her.
He has even spoken to children Stella, Mary and James, from his marriage to first wife Linda, about the possibility of the New York businesswoman becoming his third wife.
Stella is known to have flown out to Barbados just to attend the family summit.
Friends of Beatrice's mother, Miss Mills, have also confirmed that she was told marriage is on the cards but that it will not affect the child access arrangements
Another pop star who looks remarkably good for his age is Rod Stewart - who yesterday turned 65.
Stewart is still performing regularly despite now being old enough to collect his pension.
He has sold more than 120million records during his career and, though happily married to 38-year-old Penny Lancaster, remains a big hit with the ladies.
