Question:  State Route 308 (SR 308) is a 3.42 mi state highway in the U.S. state of Washington, serving the community of Keyport in Kitsap County, the highway travels generally east from an interchange with SR 3 east of Naval Base Kitsap at Bangor, Naval Base Kitsap is a what type of site, located on the Kitsap Peninsula in the state of Washington?
Context: State Route 305 (SR 305) is a 13.50 mi state highway in the U.S. state of Washington, primarily serving Bainbridge Island in Kitsap County and connecting it to Seattle in King County via the Seattle–Winslow Ferry.  The highway travels north through Bainbridge Island and leaves the island on the Agate Pass Bridge into the Kitsap Peninsula.  SR 305 continues northwest through Poulsbo, intersecting SR 307 and ending at the SR 3 freeway.  The highway was created during the 1964 highway renumbering and was preceded by Secondary State Highway 21A (SSH 21A), established in 1937.  The ferry, part of the highway since 1994, is served by the Jumbo Mark II class  and  and operates on a 35-minute crossing time. State Route 310 (SR 310) is a 1.84 mi state highway in the U.S. state of Washington, serving the city of Bremerton in Kitsap County.  The highway travels east within Bremerton from an interchange with SR 3 to an intersection with SR 304 as Kitsap Way and Callow Avenue.  SR 310 was established in 1991, following the former alignment of SR 3 on city streets in Bremerton before the construction of its current freeway in the 1960s and 1970s.  The highway was codified in 1915 as State Road 21 in 1915 and Primary State Highway 21 (PSH 21) in 1937 before becoming SR 3 during the 1964 highway renumbering. State Route 303 (SR 303) is a 9.27 mi state highway in Kitsap County, located in the U.S. state of Washington.  The highway connects SR 304 in Bremerton to an interchange with SR 3 in Silverdale.  SR 303 crosses the Port Washington Narrows on the Warren Avenue Bridge in Bremerton and becomes a grade-separated freeway bypass of Silverdale.  The route has existed as unpaved roads since the 1930s and was signed as Secondary State Highway 21B (SSH 21B) in 1937.  SSH 21B connected Bremerton to Keyport and had a branch to Illahee State Park added in 1961.  After the 1964 highway renumbering, SSH 21B became SR 303 from Bremerton to Keyport and SR 306 from Bremerton to Illahee State Park.  SR 303 was shortened in 1971, to include SR 308 , and in 1991, re-routing the highway onto the new Silverdale freeway.  SR 303 also had a spur route in Bremerton that served the Manette Bridge until 1991. The Kitsap Peninsula lies west of Seattle across Puget Sound, in Washington state in the northwestern US.  Hood Canal separates the peninsula from the Olympic Peninsula on its west side.  The peninsula, a.k.a. "the Kitsap", encompasses all of Kitsap County except Bainbridge and Blake Islands, as well as the northeastern part of Mason County and the northwestern part of Pierce County.  The highest point on the Kitsap Peninsula is Gold Mountain.  The U.S. Navy's Puget Sound Naval Shipyard, and Naval Base Kitsap (comprising the former NSB Bangor and NS Bremerton) are on the Peninsula.  Its main city is Bremerton. State Route 308 (SR 308) is a 3.42 mi state highway in the U.S. state of Washington, serving the community of Keyport in Kitsap County.  The highway travels generally east from an interchange with SR 3 east of Naval Base Kitsap at Bangor to the main entrance of the Naval Undersea Warfare Center in Keyport.  SR 308 was codified as the Keyport branch of State Road 21 in 1929 and continued as the Keyport branch of Primary State Highway 21 (PSH 21) in 1937.  During the 1964 highway renumbering, the branch became a section of SR 303, which ran from Bremerton to Bangor and had a spur route serving Keyport.  SR 308 was established in 1971 along the old route of SR 303 Spur and was extended in 1991 to the SR 3 freeway after SR 303 was re-routed onto a new freeway in Silverdale. State Route 302 (SR 302) is a 16.87 mi state highway in the U.S. state of Washington, connecting the communities of Allyn-Grapeview and Purdy on the Kitsap Peninsula, located in Mason and Pierce counties.  The highway travels southeast from SR 3 in Allyn-Grapeview along North Bay and turns east along Henderson Bay to Purdy.  SR 302 intersects its spur route and turns south, ending at an interchange with SR 16 at the north end of Gig Harbor.  The highway was created during the 1964 highway renumbering to replace Secondary State Highway 14A (SSH 14A) between Allyn and Purdy. State Route 16 (SR 16) is a 27.16 mi state highway in the U.S. state of Washington, connecting Pierce and Kitsap counties.  The highway, signed as east–west, begins at an interchange with Interstate 5 (I-5) in Tacoma and travels through the city as a freeway towards the Tacoma Narrows.  SR 16 crosses the narrows onto the Kitsap Peninsula on the partially tolled Tacoma Narrows Bridge and continues through Gig Harbor and Port Orchard before the freeway ends in Gorst.  The designation ends at an intersection with SR 3 southwest of the beginning of its freeway through Bremerton and Poulsbo.  SR 16 is designated as a Strategic Highway Network (STRAHNET) corridor within the National Highway System as the main thoroughfare connecting Tacoma to Naval Base Kitsap and a part of the Highways of Statewide Significance program. Naval Base Kitsap is a U.S. Navy base located on the Kitsap Peninsula in Washington state.  It was created in 2004 by merging the former Naval Station Bremerton with Naval Submarine Base Bangor.  The Mission of Naval Base Kitsap is to serve as the home base for the Navy’s fleet throughout West Puget Sound and to provide base operating services, including support for both surface ships and Fleet Ballistic Missile and other nuclear submarines having their home ports at Bremerton and Bangor. Keyport is an census-designated place (CDP) in Kitsap County, Washington, United States.  The community is located at the eastern terminus of State Route 308 on the Kitsap Peninsula, 3.42 mi east of Subase Bangor.  Keyport's ZIP Code, 98345, had a ZCTA population of 554 at the 2010 census, in addition to a small contingent of Navy personnel. State Route 3 (SR 3) is a 59.81 mi state highway in the U.S. state of Washington, serving the Kitsap Peninsula in Mason and Kitsap counties.  The highway begins at U.S. Route 101 (US 101) south of Shelton and travels northeast onto the Kitsap Peninsula through Belfair to Gorst, where it intersects SR 16 and begins its freeway.  SR 3 travels west of Bremerton, Silverdale and Poulsbo before it terminates at the eastern end of the Hood Canal Bridge, signed as SR 104.  The highway is designated as a Strategic Highway Network (STRAHNET) corridor under the National Highway System as the main thoroughfare connecting both parts of Naval Base Kitsap and is also part of the Highways of Statewide Significance program.
Answer: U.S. Navy base