From the start, go down the stairs and drop into the "moat". Follow it left for a while, until you reach a pair of overhanging green structures. An unreachable blue combat armor vest is visible in a nook underneath the western one. Press the use key on the brown wall underneath the nook that does not contain the blue armor, and both nooks will lower. Run over to the blue armor before it rises again to register the secret.
From secret #1, continue east along the moat until you reach a wooden chamber with several lion-faced pillars in it. One of them has blood splattered on its side; open it to reveal a teleporter to a megasphere (Note: you'll actually need to use the idclipcheat code to register this secret, as the sector is so small you can't stand in it during normal gameplay).
From the megasphere, head west down some stairs, then turn left and go straight up another set until you hit a wall. The green-tinged wall to your left opens up, revealing a teleporter to a combat armor vest.
In the same room as the door to secret #2, there's an opening in the east to a vaguely "3"-shaped hall. At the north end of this corridor, there is another green-tinged wall that can be opened for a secret.