[9-12] E2M2: The Ogre Citadel

Near the start, after descending the first staircase, jump into the river. Head left into a small cave and walk to the back wall. An elevator will take you up to a +100 health box.

From the location of the first secret (+100 health box), continue into the water. Exit the small room you are in and go left. Continue left along the path, under a bridge, and into a small room on the far wall. Go up the stairs to find the grenade launcher.

At the end of the previous secret, you will exit into a hallway. Go slightly right, and on the right wall, there will be a window. You will see an Ogre across from you. Jump out this window, staying close to the wall to land on the bridge. Follow the bridge, get the armor, and continue to the +100 health box.