Full list of all 10 Song of the Deep achievements worth 1,000 gamerscore. It takes around 10-12 hours to unlock all of the achievements on Xbox One.
Meet the Merrow
Defeat the Watcher
Activate the Deeplight
Defeat the Fomori Boss
Commune with the giant seahorse
Destroy the Forbidden City forever
Feed the Queen Leviathan
Purchase all upgrades
Kill a Tremorclaw Crab as Merryn
Pay your respects to the Watcher and drop a flower on her final resting place.