There is two caves. When you go in the left cave, there is some lava at the back. You'll see a crack in the right side - shoot it and fetch the goodies.

Press the switch over the entry door, get back down again and inside. Right next to where the map started, a door has opened in the wall. Go in and pick the goodies, and don't forget to take a walk along the narrow ledge...

Go through all the sewage pipes to get here - go for the Data Spinner. After you have shot the glass cage for the spinner, shoot the wall two steps to the right of the cage. It will pull back and reveal a step-on switch. Step on it, right behind you the secret opens. Take the goodie and activate the switch.

After finishing #3, the next secret is unlocked. Go back to the start, get up over the entry door and check the cave.

This is slightly annoying... You have to go to the next level and shut the red lasers off, before you can get the goods here. Just remember to do it...