Decepticon advance base

The advance base (前進基地 zenshin kichi) is a base located underwater off the coast of Australia. It was built to support Decepticon operations during the Masterforce War and is guarded by the Seacons.

Super-God Masterforce cartoon
The advance base was built under Seacon supervision. The repeated explosions on the ocean floor used in construction caused a nearby volcano to become active. The underwater volcano, in turn, caused an earthquake that demolished Sydney and attracted the Autobots' attention. Lightfoot went underwater to investigate the volcano, only to be met by the Seacons guarding the base. In his retreat, he came across the base.

Later, the underwater volcano erupted, raining down magma on the advance base and destroying it. King Poseidon was upset, blaming the Seacons' cowardice for its destruction.