Question: Which inlet on the Gulf of Maine is home to House Island?
Context: Rainsford Island, formerly known Hospital Island, Pest House Island, and Quarantine Island, is a 11 acre island in the Boston Harbor, situated between Long Island and Peddocks Island.  The island is composed of two drumlins, reaching an elevation of 49 ft above sea level.  The shoreline is predominantly rocky with a sandy cove in the south side, and a variety of wildflowers abound.  Access is by private boat only.  Since 1996 it comprises part of the Boston Harbor Islands National Recreation Area. Chira Island is a 3000 ha Costa Rican Pacific island located at the upper end of the Gulf of Nicoya, an extensive inlet of sea water that is the result of a geological fault that has caused the land to submerge, leaving exposed only the tops of what were formerly low hills.  These are the various islands that dot the gulf, the largest of which being the Island of Chira - Costa Rica's second largest island.  The Gulf of Nicoya separates Guanacaste from mainland Costa Rica and is fed by the Tempisque River.  Chira Island lies just off San Pablo, Guanacaste. Casco Bay is an inlet of the Gulf of Maine on the southern coast of Maine, New England, United States.  Its easternmost approach is Cape Small and its westernmost approach is Two Lights in Cape Elizabeth.  The city of Portland sits along its southern edge and the Port of Portland lies within. Prince Regent Inlet ( ) is a body of water in Nunavut, Canada between the west end of Baffin Island (Brodeur Peninsula) and Somerset Island on the west.  It opens north into Lancaster Sound and to the south merges into the Gulf of Boothia.  The Arctic inlet's northern portion is approximately 40 mi wide; the southern portion is approximately 65 mi wide.  It is deep throughout and there are no islands within the inlet. Eilean an T(a)ighe, meaning "House Island" (lit.  "Island of the House"), is one of the Shiant Isles.  It is joined to Garbh Eilean by an isthmus and both form part of a single island. The Gulf of Boothia is a body of water in Nunavut, Canada.  Administratively it is divided between the Kitikmeot Region on the west and the Qikiqtaaluk Region on the east.  It merges north into Prince Regent Inlet, the two forming a single bay with different names for its parts.  It is surrounded by, clockwise, Baffin Island, Fury and Hecla Strait, the Melville Peninsula, the Canadian mainland, the Boothia Peninsula and perhaps Bellot Strait if the Gulf can be said to extend that far north.  The south end is Committee Bay, northwest of which are the Simpson Peninsula and Pelly Bay.  In addition to its connection to Prince Regent Inlet one can use an icebreaker to go east through the Fury and Hecla Strait, or, with luck, pass the Bellot Strait westward. The Barker Inlet is a tidal inlet of the Gulf St Vincent in Adelaide, South Australia, named after Captain Collet Barker who first sighted it in 1831.  It contains one of the southernmost mangrove forests in the world, a dolphin sanctuary, seagrass meadows and is an important fish and shellfish breeding ground.  The inlet separates Torrens Island and Garden Island from the mainland to the East and is characterized by a network of tidal creeks, artificially deepened channels, and wide mudflats.  The extensive belt of mangroves are bordered by samphire saltmarsh flats and low-lying sand dunes, there are two boardwalks (at Garden Island and St Kilda), and ships graveyards in Broad Creek, Angas Inlet and the North Arm. Pea Island is an island which is part of the Outer Banks of North Carolina.  Because of the shifting nature of the barrier island system of which Pea Island is a part, and the way in which inlets open and close over time, Pea Island has, at times, been contiguous with the neighboring islands of Bodie Island or Hatteras Island.  Pea Island was created when two inlets, the New Inlet in 1738, and Oregon Inlet in 1846, separated it from the neighboring islands.  The island was rejoined to Hatteras Island intermittently from 1922 until 1945 as the narrow New Inlet opened and closed with shifting sands.  Pea Island ceased to exist entirely from 1945 until 2011, when Hurricane Irene reopened the New Inlet, recreating Pea Island.  From 1945 to 2011, Pea Island was merely the northern 11 miles or so of Hatteras Island.  Pea Island was home to the Pea Island Life-Saving Station, the first U.S. Coast Guard life-saving station to have an all African-American crew.  Since 1937, it has also been home to the Pea Island National Wildlife Refuge. House Island is a private island in Portland Harbor in Casco Bay, Maine, United States.  It is part of the City of Portland.  The island is only accessible by boat.  Public access is prohibited, except for an on request tour sanctioned by the island's owners.  House Island includes three buildings on the east side and Fort Scammell on the west side.  The buildings are used as summer residences.  The island's name derives from the site of an early European house, believed that built by Capt. Christopher Levett, an English explorer of the region. Oregon Inlet is an inlet along North Carolina's Outer Banks.  It joins the Pamlico Sound with the Atlantic Ocean and separates Bodie Island from Pea Island, which are connected by the 2.5 mile Herbert C. Bonner Bridge that spans the inlet.  As one of the few access points to the ocean along this stretch of coast, Oregon Inlet is a major departure point for charter fishing trips, with a nearby harbor serving as the base for many large boats that travel miles out towards the Gulf Stream almost every day.  The inlet is also the location of a U.S. Coast Guard station.
Answer: Casco Bay