There are 20 Trophies that can be collected.

BRONZE

Alpha
Get to a hard-to-reach spot near the area where you met Malie.

Beta
Get to a hard-to-reach spot in a wintery place outside Crystal Path.

Delta
Get to a hard-to-reach spot in Markstone Ridgemine.

Gamma
Get to a hard-to-reach spot above a purple forest.

Epsilon
Get to a hard-to-reach spot above a museum.

Zeta
Get to a hard-to-reach spot beneath the underwater lab.

14 SECRET

BRONZE

Because it’s tradition
Find the sheep.

Knytt Stories
Find the hidden Juni story.

Tobias Chilli
Find a hidden disco area in the hidden Juni story.

Dance in the sky
Find a hidden disco area in the Interlude.

Fireworks
Complete a hidden challenge in the Interlude.

Heroic Dance
Find a hidden disco area in one of the mini-chapters.

Redundant Bird
Find the purple bird.

Habanero Apologize
Find out where Susanna lives.

Sandwich
Find the hidden sandwich recipe.

La Vupene
Complete the Mini Figure.

Falu Kohe
Complete the Figure.

Mysterious Forest
Explore a beautiful forest.

Shortcut Genius
Complete Chapter 3 without paying a single bell guard.

SILVER

What She Longed For
Find the secret ending.

http://www.ps3trophies.org/game/knytt-underground/trophies/