Inside a nautically inspired Shelter Island mansion with a deepwater dock and a private beach, a trap door in the bar’s teak and holly floors beckons visitors “below deck” to a 720-bottle wine cellar. The listing price is $6.9 million.

The 9,230-square-foot home has six ensuite bedrooms, five fireplaces and four half-baths. Portions of the home date back to 1888, listing agents Samuel Marcus and Michael Tucker of Daniel Gale Sotheby’s International Realty say.

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In addition to the bar, the first floor has a living room, library/den and home theater. A chef’s kitchen is open to dining space and a sitting room with a fireplace and doors to a deck.

A bridal staircase leads to the second floor, where a great room with a fireplace and pool table includes a kitchenette, powder room, office and doors to a second, elevated deck.

The 1.71-acre parcel includes a new in-ground pool and a heated attached four-car garage.