Here is a guide on how to get all achievements in Death in the Water 2. more content will be added in near future.
Gameplay
Lionfish Slayer
You have proven yourself to be a master of Lionfish hunting! You have taken down 10 Lionfish in record time.
*Awarded for completing the tutorial (Unskippable)
Deaths Lair
Defeat the Kraken
Levels
**NOTE = Treasure is not required for level completion. Although does help late game, but if you can’t find it don’t fret. After the Kraken Siren sounds, there will be a red marker in the top right hand corner, once this reaches zero the level will automatically be passed, regardless of objective. (You can accelerate this process by killing sharks and other sea life, try and maintain the multiplier (Don’t die) and it should happen relatively quickly))
First Blood
Complete Dive 1
Depths of Terror
Complete Dive 2
The Phantom Flight
Complete Dive 3
Serpents Shadow
Complete Dive 4
Deaths Grip
Complete Dive 5
Diablos Reef
Complete Dive 6
Night Dive
Complete Dive 7
Sacrifice
Complete Dive 8
Hunting Grounds
Complete Dive 9
Lost Ruins
Complete Dive 10
Siren’s Scream
Complete Dive 11
Blood Lust
Complete Dive 12
The Jaws of Death
Complete Dive 13
The Leviathan’s Legions
Complete Dive 14
Thanks to Raxrr for his great guide, all credit to his effort. you can also read the original guide from Steam Community. enjoy the game.