The Pool at Chateau De Vault De Lugny
Chateau de Vault-de-Lugny's pool is mentioned by professional travelers. Out of 3 reviews tracked on TripExpert, 3 mentioned the pool, like Fodor's, Frommer's and The Telegraph.
Chateau De Vault De Lugny 
Fodor's
Frommer's
The Telegraph
Fodor's "The finest room—Le Roy (Eric Clapton’s favorite)—has a four-poster bed and direct access to the swimming pool in the vaults"
Frommer's "The indoor pool is in an attractive stone cellar while the gourmet restaurant, which features seasonal food from its own garden, is housed in the 17th-century former kitchen"
The Telegraph "Guests can swim in a pool located in the underground vaults, or fish in the castle moat"
