Cage Key 1

Cage Key 1 is an item found in Secret Island. Uber Bear holds this key. Much like the other keys, it is vital to obtain this in order to progress through the level and, more importantly, save Sergeant Sternhauser.

How to obtain
Defeat Uber Bear before the timer expires and he will drop it after fading away, which means that you can open the cell and press the switch to save the Sergeant.