Here is the full list of all 30 Underland achievements.
Level 1 completed
Level 2 completed
Level 3 completed
Level 4 completed
Level 5 completed
Level 6 completed
Level 7 completed
Level 8 completed
Level 9 completed
Level 10 completed
Level 11 completed
Level 12 completed
Level 13 completed
Level 14 completed
Level 15 completed
Level 16 completed
Level 17 completed
Level 18 completed
Level 19 completed
Level 20 completed
Level 21 completed
Level 22 completed
Level 23 completed
Level 24 completed
Level 25 completed
Level 26 completed
Level 27 completed
Level 28 completed
Level 29 completed
Level 30 completed