From the beginning, Pelorus is shrouded in mystery. Nothing is said about the mine in the briefing. Pelorus contains one of the largest secret area networks to be found in Obsidian, With approximately 15 secret areas and even more triggers, it may well be the largest outside the secret levels. The mine can be destroyed immediately, but you need at least the blue and red key to escape. If you lack Guided Missiles to fire through a grate, you'll also need the Yellow key. The robots in this mine are also highly dangerous in parts.
In Pelorus, there are eight ECMs which you must destroy. Three contain keycards, the other five are simply decoys. You won't know which ones to destroy until you've destroyed them.
You will then proceed to destroy the reactor. It is possible to do this at the beginning of the level, but unless you want to end the level quickly and die, this is NOT recommended. There are approximately 15 secret areas in this level. Try to find as many as possible, especially the larger ones.