Note that you will need the adventurer's amulet if you haven't put any points in lockpicking, which can be found by climbing up the cliff next to the waterfall in the beginning area. Since there are many ledges to grab you are able to do this before you get the jetpack.

You will also need one picklock to open the chest. The worker armor has just 2 armor points less than the hunter's armor so it's great if you haven't put any points in constitution/strength.