The Zubmariner Add-on for Sunless Sea has 24 achievements.
Discover Undercrow
Discover Hideaway
Escape underwater combat by resurfacing
Discover The Gant Pole
Discover Dahut
Discover Anthe
Discover Scrimshander
Discover Rosegate
Use an oasis to increase your oxygen levels
Discover Nook
Discover Wrack
Use underwater currents to bear you on your way
Discover Aigul
Discover Low Barnet
Venture beneath the waves
Die of suffocation
Be killed by an underwater creature
Be killed by the Constant Companion
Come face to face with the Constant Companion
Avoid being killed by the Unexploded Unclear Bomb
Accept a power of the deep zee
Perform an abyssal ritual to encounter Lady Black
Complete the Zubmariner ambition
Collect all of Drownie Love-song, Drownie Counterpoint and Drownie Hymn