O-class submarine
# O-class submarine

O-class submarine may refer to:

* United States O-class submarine
* Oberon-class submarine
* Odin-class submarine
* Several early submarine classes of the Royal Netherlands Navy:

    O 1-class submarine consisting only HNLMS O 1
    O 2-class submarine
    O 6-class submarine consisting only HNLMS O 6
    O 7-class submarine consisting only HNLMS O 7
    O 9-class submarine
    O 12-class submarine
    O 16-class submarine consisting only HNLMS O 16
    O 19-class submarine
    O 21-class submarine
