Drop into the empty biowaste tank and walk through the corridor on either side. Open the watertight door, head through and turn left, enter the opening and ride the lift up.

Push the button under the upper deck, climb the sloped support to get some goodies, jump down and make your way along the shattered walkway on your left to the alcove.

Leave the room and enter the hallway, turn right, enter the biowaste chamber, kill the two Mercenaries, and push the button under the upper deck. Grab the shield belt and jump boots in the acove on your left and enter the nearby door.

Go up the lift and jump onto the broken pipe. Jump down at the end and make your way around the ledges surrounding each pipe for ammo. Jump down into the biowaste and swim up to ground level, returning to the previous biowaste chamber. Exit through the door and you'll come to a lift on your left. Walk past it and through the door ahead.

In the chamber that you'll come to, push the button under the upper deck, and go back and ride the lift up to the hydroponics section. Turn left, enter the passage and push the button to activate a lift on your right. Go up on it to the ledge above. Press the button on the right to lower the next lift. Kill the Mercenary below, ride the lift back up, enter the door and kill another Mercenary, get the assault vest and jump to the lower level packed with freebies.

Press either of the two floor-bound buttons to get a lift back up - stay on, though, as it'll go up one further level. There are plenty of freebies here.