Here is the full list of all 18 Deep Under achievements.
The equipment you found saved you from death
You died at the beginning of your journey
You examined the rack in the lab
Coyote kept his word
You used the spear
You helped Andy to escape
You talked to Scorched in Yeutlan
You saved Coyote
You gave the body to Jeuit
You made it, but...
You entered Yeutlan and solved your problem
Your pet is a survivor
You got a closer look at the monster
You got a pet
You failed to help Nash
You waited out the danger
You got caught by Mole
You went deeper into the caves