Secret Base Zone is the second Zone of Sonic Advance. This Zone comes after Neo Green Hill Zone and precedes Casino Paradise Zone.
A typical factory installation of the Eggman Empire, this industrial setting features a host of manufacturing-based obstacles: swinging hooks to leap across the ceiling, pressurized tubes to sweep the player through a pipe network; steam tops, molten metal crucibles, and free-floating iron platforms. Less usual gimmicks include ziplines criss-crossing the foreground, and dual chutes that drop the player through the background.
Many of the features in this level first debuted in Metropolis Zone from Sonic the Hedgehog 2.
A unique effect in the very first, outdoor part of Act 1 is an interesting floodlight motif, later used in Sonic Advance 2's Ice Paradise Zone.
||Mogu — Mole Badnik that pops out of the ground.
||Senbon — Pufferfish Badnik (doesn't appear in Easy mode).
||Tentou — Moth Badnik that shoots energy balls.
Special Spring location
The Special Spring for this Zone is located in Act 2. To find it, the player should take the top-most routes as much as possible, and they will eventually find it on top of a downward loop. As they go through the loop, they should use the springs and bouncy platforms to reach it.