SSN-21 Seawolf is a submarine simulator game designed by John W. Ratcliff and published for MS-DOS systems by Electronic Arts on April 3, 1994.
Seawolf models the ocean environment, including thermal layers which can be used to deflect enemy sonar and hide the player's submarine.
Like its predecessor, Seawolf allows two players, on different PCs, to play each other via a modem, or null-modem cable, and adds the option of using an IPX local network which can provide a more reliable connection.
Computer Gaming World in May 1994 said that "certain hard-core simulation features have been left out to enhance overall playability, but the state-of-the-art graphics, tremendous music by the Fat Man, and mind blowing sound effects all combine to lock this product dead-on-target".
The magazine concluded that "as a simulation, Seawolf is a dud; as a game, it's a solid effort and a worthwhile addition to any naval gamer's shelf".