An enchanted world within a world, St. Mary’s Island, is a rarified setting for extraordinary living. Comprising over five acres and accessed via a short causeway, St. Mary’s Island stands as one of the most unique and idyllic estate properties on Cape Cod. The location is unmatched, offering complete seclusion while in the heart of exclusive Osterville. The estate offers panoramic views of glittering North Bay and easy proximity to renowned village shops, restaurants, marinas and Wianno and Oyster Harbors clubs. Designed in the French Normandy style, this fabled residence offers grand living spaces, stellar views, magnificent grounds, and a 155-foot-long deep water dock for yachting on Nantucket Sound and the islands.

As one approaches the main residence, steeply pitched gables, stucco and stone walls, and terracotta windows set the stage for the grand scale of this inimitable estate. An arched entry portico opens to a stately entrance hall with oak paneling, soaring ceilings, and ornately carved staircase balusters. The ground floor holds a two-story oak-paneled library/billiards room with arched casements, lead-paned windows, and a massive fireplace. Connected to the library through a secret passage, an intimate study with fireplace and semi-circular bay windows showcases lovely water views. A balcony overlooking the library leads to a turreted bedroom suite on the mezzanine level. At the hall’s end, a stunning formal living room boasts floor-to-ceiling windows, fireplace with antique mantle, and French doors opening to an elevated English stone terrace overlooking manicured grounds and azure waters beyond. A banquet-size dining room with lofty ceilings and French doors opens to the central terrace and stone walkway leading to water and dock. Beyond lies an immense gourmet kitchen with professional-grade appliances that affords entertaining on all scales. The adjoining great room features beamed and cathedral ceilings living areas, informal dining room opening to terraces and gardens, and beautiful bay views. A fully-equipped butler’s pantry, mud room, laundry, full bath, and powder room complete the main level. 

On the second floor, a large master suite with sumptuous bath, walk-in closet, dressing rooms, and kitchenette delivers unmatched privacy and relaxation. Nearby, meandering corridors with well-preserved period details lead to two en suite bedrooms with hardwood floors and fireplace. Connected to the main house, two discrete guest suites–one with full kitchen, sleeping areas and full bath. living and family rooms–accommodate guests or staff. A third guest suite, accessible by private exterior stairs, contains living room, sleeping area and full bath. A stone’s throw from the main residence, a separate carriage house with water views is discreetly tucked into the property’s lush plantings, offering wonderful privacy and water views.. With full kitchen, living room, bedroom and bath, this guest house and attached three-car garage augment refined accommodations available to guests, family or staff. Across the sprawling five acres, carefully maintained grounds include manicured lawns, English gardens and numerous outdoor living spaces of intimate and grand scale set amongst towering rhododendrons and beech trees. Surrounded by water in every direction, this fabled setting delivers an experience of timeless elegance that defies description. Accessed by a stone walkway, the 155-foot-long deep water dock serves as a gateway to Cape Cod’s enviable aquatic lifestyle, with endless sailing, fishing, and boating to be enjoyed from one’s backyard. 

St. Mary’s Island…a world unto itself, and pure enchantment

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Property Information

Location: 251 Seapuit Road, Osterville, Massachusetts

Bedrooms: 8

Bathrooms: 7 full/1 half

Living Area: 8,931 sqft

Price: $18,500,000

Listed by: Robert Paul Properties

Contact: 508.420.1414