[Overview]
Secret 1 - Secret Canon
On the roof of the building where the level starts, find the secret canon.
Secret 2 - Secret Health
Open the valves behind the shark pool to get to the secret health in there.
Secret 3 - Secret Hoverfighter
Use some boxes to jump over the entrance of the little yard with the hoverfighter. Being inside, shoot the gnaar to get back out. Russell reported that the gate opens also from the outside when you shot the gnaar, but that didn't work for me, so you may want to try this first.
I had to leave and re-enter the hoverfighter outside the little yard to make this count as a secret. Since this also spawns some T Mechs, it makes sense to do this inside a hangar and thus protect yourself and the fighter. It'll then be a great help through the corridor at the level exit.
Created November 5, 2005 Peter Holzwarth.