The Echo class were nuclear cruise missile submarines of the Soviet Navy built during the 1960s. Their Soviet designation was Project 659 for the first five vessels, and Project 675 for the following twenty-nine. Their NATO reporting names were Echo I and Echo II. All were decommissioned by 1994.

== Echo I class ==<!-- Echo I class submarine points here -->

The Soviet Echo I class (Project 659 class) were completed at Komsomolsk in the Soviet far east in 1960 to 1963. The Echo I class were classed as SSGNs armed with six launchers for the P-5 Pyatyorka (SS-N-3C, "Shaddock") land-attack cruise missile. The Echo I class had to operate in a strategic rather than anti-shipping role because of the lack of fire control and guidance radars.

thumb|left|Nuclear-powered submarine of Project 659 (Echo I) re-equipped into attack submarine of Project 659T

thumb|left|Project 659

As the Soviet SSBN force built up, the need for these boats diminished so they were converted to the Project 659T SSNs between 1969 and 1974. The conversion involved the removal of the cruise missiles, the plating over and the streamlining of the hull to reduce underwater noise of the launchers and the modification of the sonar systems to the standard of the SSNs.

All the Echo Is were deployed in the Pacific Fleet. The last two boats were scrapped in the early 1990s.

Boats

{| class="wikitable"

|+Echo I class &mdash; significant dates

!#

!Shipyard

!Laid down

!Launched

!Commissioned

!Fleet

!Status

|-

|

|Leninskiy Komsomol Shipyard, Komsomolsk-na-Amure

|December 20, 1958

|May 12, 1960

|June 28, 1961

|Pacific

|Decommissioned 1989 for scrapping

|-

|

|Leninskiy Komsomol Shipyard, Komsomolsk-na-Amure

|September 30, 1959

|September 25, 1960

|December 16, 1961 than the P-500 and its range was extended to . The P-1000 was installed on three units of the Northern Fleet between 1987 and 1993. The conversion of two boats of the Pacific Fleet, K-10 and K-34, was abandoned due to lack of funds.

;24 September 1976

: K-47 (Echo II) was in the North Atlantic when a fire broke out in compartment VIII (living quarters) due to short circuit. Three were killed by carbon monoxide poisoning.

;2 July 1979

: K-116 (Echo II) suffered a reactor accident (a leak of core coolant from the port reactor) in the Bay of Vladimir, Sea of Japan. Some of the crew received a large dose of radiation, but there were no fatalities.

;21 August 1980

: K-122 (Echo I) had a fire in compartment VII (turbo-electric) when to the east of Okinawa. Fourteen died due to carbon monoxide poisoning.

;10 September 1981

: K-45 (Echo I) collided with Soviet fishing trawler Novokachalinsk at night. The bow of the outer hull and the sonar system of the submarine were seriously damaged. The trawler sank.

;18 June 1984

: K-131 (Echo II) was in the Barents Sea when a fire broke out in compartment VIII due to violation of safety methods by an electrician. Fourteen died.

;10 August 1985

: K-431 (ex-K-31) (Echo II) had a reactor explosion while refueling in the shipyard at Chazhma Bay, Sea of Japan. Ten died as a direct result, while 300 men from rescue parties received various doses of radiation and several died later.

;November 1986

: K-175 (Echo II), while at its homebase (Pacific Fleet), suffered an explosion in the reactor compartment, causing radioactivity discharge and contamination of nearby territory. There were no fatalities.

;1989

: K-1 (Echo II mod) had a reactor accident.