[07-01-05] E1L05 - The Abyss

In the dark cave at the beginning of the level, use the goggles (night vision goggles) to find the hidden message "GO WITH THE FLOW", which is a hint for finding secret 5.

In a secret cave containing a dancing girl and three Atomic Health pickups, you will find a message on the wall that reads "SUYT". This crude acronym stands for "Show Us Your Tits".

Near the end of the level, while crossing a narrow ledge high above lava to reach the ending chambers, drop down to the very bottom of the pit beneath the bridge. Here, you will find a message on the wall that says "Dopefish Lives". Dopefish is a character from the Apogee game, Commander Keen Episode IV.

You need a jetpack (obtainable legitimately from E1L06, Launch Facility) to reach a hole where shrink ray bursts are being fired. On the wall here, there is a small inscription that reads "You're not supposed to be here. -Levelord". The Levelord was a designer of many levels in the original Duke Nukem 3D.

Look for a small headstone that says "San Andreas Fault". This refers to the geological fault line in California, famous for causing large earthquakes. In this level, the fault causes a collapse.