DescentBB

Does anyone know how to get to the 2 secret levels without using the cheat codes in Descent 3???

I remember that in the level "proving grounds", if you defeat both of the bosses before you get to the group of four bosses, you can access a secret area that includes black shark missiles, repair facilities, and a device that will allow you to access one of the secret levels. I don't remember which levels that gets you or how you get to the other one, though.

Level 8 contains the access point to the first secret level. After you've blasted both heatsinks, explore the pipe-like area a bit. The device is somewhere in there. I think.

Yeah, you can get to the first secret level through level 8 (the snow one) and the second one through level 12 (the proving grounds). You can get walkthroughs for both of these levels here.