So... well, here we are. Outside. Don't know why...
Go kill the shockbot and grab the relics and sun from the north. Yes, you can slide down the salt piles here if you wish. Next up is two more shockbots and after them is a shockbot and a new foe: the dozer bot. He's got scoops for hands and will clap them together three times while coming at you (beat him up after the third clap). He can also put them together and rush at you (like he is scooping something).
Climb the salt pile and jump to the ledge. Grab the sun and then beat up the next missile guard before taking out the dozer. Continue on and beat up two more, then hit the switch to start a conveyor belt and use it to move on.
Head down the path and you'll meet a new enemy: a guard with a mace. He will swing it and smash it into the ground, making the energy in it affect an area around the impact. When he does that be sure you are on the move and jumping if too close. He can swipe at you if you are close as well. Just take him out after he attacks like normal.
Further in will be three missile guards. Avoid the salt piles here (it slows you down) and take them out one by one when its safe. Once they drop a fence will open letting you hit a switch to start another conveyor.
Destroy the bot here and to the north are three missile guards (one high up) and a mace guard. This is a good place for a Blast. Destroy the three ground guards, then before hitting the switch go examine the north wall. On the very left is a crystal but just to the right of that you can break down a part of the rock for...
HIDDEN CHEST #25:
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
Once you get to the area with three missile guards and a mace guard, go check the north wall. Find the crystal part at the left end and break the wall down immediately to the right to uncover this pathway and chest.
Head back out, hit the switch, then go pay the last missile guy a visit. Collect the relic, hit the switch, and head inside the door to end this part of the chapter.