No secret areas, but there is a door you can go through right across from the elevator. There are also some useful items on the beams which come out of the structure of the elevator (must be on lift and going up to get on them.)
In the room with two buttons to open door to the lift leading to Noork's elbow and a gesbio rifle, there is a pipe (last on left if you are leaving the room) with super health. To get to it push a steelbox to it and jump up!
There are some hidden items behind the pipes where the elevator get stuck (jump on the rings going around the pipes). Then there's also some behind the pipes by the elevator that does work. There is also a wall that opens behind the kevlarsuit on the top floor of the green house. Go in the room with the 4 elevators and stand on them long enough to be taken to the very top.
The first nali you encounter opens a secret door so be sure to follow and protect.
Swim in there, then look for a passage way. Swim through that and just before the blocked entrance, there should be an opening to your right.
Swim under the boat and you should see a passage way.
If you don't already have a flare, grab one from that counter. Then do a 180 and go through the passage on the left. (leads to picture below)
Throw a flare in the water under the dragon head, and then look to your left.
Go through that large door, and then look to your right and there should be a woodenbox in the corner. Destroy and grab the jumpboots. (leads to picture below)
After getting the jumpboots, go up the elevator and run straight until you get to the edge. Look down, and you'll see a box. Activate your jumpboots (so no damage is inflicted) and run (don't jump) on to the ledge with the box, then open it up :). (see below on how to get down safely)
Make sure your jumpboots are ACTIVATED. Then run (once again, don't jump) onto the circled area.
As soon as you enter the Engine Power Core Control room, go straight and there should be a door that leads to this room (right behind the screen that says Level 2. Destroy the circled box to get a pair of jumpboots. Then go up the elevator. (leads to picture below)
Okay, the circled areas are spots where you can jump. Make sure you only use your jumpboots twice, as there is another spot you can jump to. In order to get over that big object, deactivate your jumpboots and run and jump against the slope (while holding forward the whole time) The arrow leads to the room with the last spot. Go in that room and there should be a ledge right above the door way jump on it to get stinger ammo (kinda useless but...yeah) And there's a shieldbelt chillin' behind the screen with the small planet.
Okay, before following the arrow to the room below, there is a box below the end of the bridge. This can be a little tricky so read carefully. First of all, make sure you have atleast 100hp. Then move around the bridge untill you can see 2 woodenboxes in the slime. explode the larger one revealing 'invisibility'. Then go to the end of the bridge and jump down to grab it. Then, HOP your way back to safety, running the whole way without jumping won't work and you'll most likely end up dead. Now that you're alive (hopefully) go through the little door and up the elevator. (leads to picture below)
I know it's a little hard to see, but in the circled area is a box containing jumpboots. Then the arrow pointing up is the area you can get to using the jumpboots where you'll find a very useful item. Finally, the arrow pointing to the left leads to you to a nice piece of armor.