Here is the full list of all 7 Travel Mosaics 6: Christmas Around the World achievements.
Complete all the main levels in 4 locations while earning 3 stars in each level.
Complete all the main levels in 8 locations while earning 3 stars in each level.
Complete all the main levels in 12 locations while earning 3 stars in each level.
Complete all the main levels in 16 locations while earning 3 stars in each level.
Complete all the main levels in all locations while earning 3 stars in each level.
Complete all 20 bonus levels while earning 3 stars.
Solve all 20 additional puzzles.