688 Attack Sub is a submarine simulator video game designed by John W. Ratcliff and Paul Grace and published in 1989 for MS-DOS and in 1990 for Amiga by Electronic Arts.

The player takes command of a US Los Angeles-class or Soviet Alfa-class nuclear-powered attack submarine and plays ten missions ranging from into either Cold War scenarios or combat missions in a hypothetical global conflict.

[1] 1992 and 1994 surveys in the magazine of wargames with modern settings gave the game two stars out of five, stating that the game was closer to World War II than modern submarine operations, and criticizing the "unrealistic" emphasis on periscope target acquisition.

[4] The magazine praised the game's graphics and two-player modem option, but criticized the lack of more than ten missions.

[5] Mike Siggins reviewed 688 Attack Sub for Games International magazine, and gave it a rating of 7 out of 10, and wrote that "the appeal of using modern weapons soon wears off and one is left with only the different situations to add spice.