Here is the full list of all 36 Hot Tub Simulator achievements.
Get 20 subs
Get 100 subs
Get 500 subs
Get 1000 subs
Reach streamer rank 1
Reach 100 viewers
Reach 500 viewers
Reach 1000 viewers
Reach 5000 viewers
Buy 1 bikini
Buy 5 bikinis
Buy 10 bikinis
Buy 1 zone
Buy 3 zones
Buy 6 zones
Pop 1 extra viewers bubble
Pop 10 extra viewers bubbles
Pop 100 extra viewers bubbles
End 1 streaming
End 10 streamings
End 50 streamings
Do squats 1 time
Do squats 10 times
Upgrade Squats to max level
Draw 1 time
Draw 10 times
Upgrade Draw to max level
Do Jumping Jacks 1 time
Do Jumping Jacks 10 times
Upgrade Jumping Jacks to max level
Dance 1 time
Dance 10 times
Upgrade Dance to max level
Do ASMR 1 time
Do ASMR 10 times
Upgrade ASMR to max level