to shoot the frozen crate use the yellow eco vent that youre supposed to unblock! To get into the cave place, go to the right side of the base thing, and you should see some trees and just go behind them and there's the entrance, the rest is up to you! Feel free to post more questions, i have beaten all the challenges and missions in Jak and daxter, Jak 2, and Jak 3! i'll be your guide to victory!