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Caroline Kennedy, President Obama’s nominee for ambassador to Japan, is already making waves.

The 55-year-old daughter of JFK spent part of yesterday on Martha’s Vineyard, where she went water-skiing behind a boat piloted by her son, John Schlossberg — occasionally showing off her aquatic prowess by speeding along on only one ski.

The boat’s license is MS (for Massachusetts) PT 109, after the boat her dad commanded 70 years ago in WWII. The Post has revealed that her net worth of could be as high as $500 million.