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Offered at $4,200,000Active
beds
3
baths
5
sq ft
3,238
Built
1977

350 Portsmouth Avenue

New Castle, NH 03854

Residential · Active · MLS #5107161
Listing Courtesy of Great Island Realty LLC | Janet Sylvester, Margaret Pesce

The home

About this home

Welcome to 350 Portsmouth Avenue, an exceptional waterfront residence offering a front row seat to one of the most captivating maritime settings on the New Hampshire Seacoast. With expansive water views of the Piscataqua River and Back Channel, this remarkable property captures everything that makes New Castle waterfront living so special. From magnificent ships and iconic Portsmouth tugboats to sailboats, fishing vessels and pleasure craft, the ever changing boat traffic provides a spectacular backdrop from morning until night. A private deep water dock makes this a dream for boating enthusiasts, offering direct access to Portsmouth Harbor, the Piscataqua River and the open Atlantic. Adding to the property's unique appeal is deeded access to the Back Channel, creating a wonderful launching point for kayaks and paddleboards. Designed to embrace this extraordinary setting, the home features multiple waterfront decks for entertaining, outdoor dining or simply watching the river come alive. A walk-out lower level extends the living space outdoors, while the hot tub and sauna create a private waterfront retreat to enjoy throughout the seasons. Enjoy all the amenities that make New Castle one of the Seacoast's most coveted communities, the nearby yacht clubs, Wentworth Marina, Wentworth by the Sea Country Club, Great Island Common, beaches and the historic charm of island living, all just minutes from downtown Portsmouth. And with New Castle's exceptionally low property taxes, this is a rare opportunity to combine an extraordinary waterfront lifestyle with one of New Hampshire's most desirable communities. Deep water boating out your front door. Kayaking and paddleboarding from your deeded Back Channel access. Incredible water views, spectacular boat traffic, waterfront decks, hot tub and sauna, all in the heart of New Castle. 350 Portsmouth Avenue isn't simply a waterfront home, it's a lifestyle defined by the water.

Property information

Details at a glance

Interior4 property facts
Rooms
7
Heating
Oil, Forced Air
Cooling
Central Air
Flooring
Carpet, Tile
Building5 property facts
Style
Single Family Residence
Year built
1977
Garage
2
Parking
2
Roof
Shingle
Land & utilities5 property facts
Lot size
0.25 acres
Water
Public
Sewer
Public Sewer
Waterfront
Y
Zoning
RD RE
Financial2 property facts
Annual taxes
$15,636
Assessment year
2025

Plan your purchase

Estimated monthly cost

Explore costs at the $4,200,000 asking price. Adjust the assumptions to your situation.

Known monthly costs$22,540 / monthAdjust
Principal & interest
$21,237
Property tax
$1,303
Insurance
Not entered
HOA
Not entered

Listing annual taxes: $15,636. Initial monthly tax is one twelfth of that amount. HOA amount was not supplied.

Partial estimate: add insurance, monthly HOA to include those costs. Blank amounts are unknown.

The initial 6.5% rate is illustrative, not a current rate or lender quote. Excludes utilities, maintenance, closing costs and mortgage insurance, which may apply with a down payment below 20%. Taxes and insurance can change.

Listing history

Price and status timeline

No additional listing history is available for public display.

Compare with confidence

Price & market context

See how this home compares with active listings in New Castle.

This home compared with active listings in New Castle
MetricThis homeLocal listings
List price$4,200,000$4,200,000Near the local benchmark
Price / sq ft$1,297$1,297Near the local benchmark
Days on market33Near the local benchmark

Active city listing statistics from PrimeMLS as of September 12, 2026. Asking prices are not completed-sale values.

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Common questions

About 350 Portsmouth Avenue

Can I request a private showing?

Request a tour of 350 Portsmouth Avenue and a Bean Group agent will help coordinate an available time with the listing side.

Can you help me evaluate this property?

Yes. We can discuss condition, comparable sales, offer strategy and the questions worth asking before you decide whether to proceed.

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