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Generate a sympathetic overload in Harmonic Core #3. That's simple. Now all I gotta do is figure out what the hell a sympathetic overload is, and for that matter, a Harmonic Core #3!
Anya Andersdotter[src]

Hephaestus Core, or Harmonic Core #3,[1] is a geothermal generator, located within Rapture's Hephaestus district. It provides power to much of the equipment in Hephaestus, as well as some parts of the city. 

The Core is divided into two sections: an outer ring connecting the three monitoring and maintenance areas of Hephaestus and an inner ring providing direct access to the rotating generators.


Hephaestus Core Direction Sign
Main article: BioShock

Outer Ring[]

The spiraling set of stairs provide access to Heat Loss Monitoring, the Workshops, and Geothermal Control. Other facilities include a Power to the People machine and a Gatherer's Garden. The phonograph near the Garden plays "It's Bad for Me".

Core Access[]

B1 EMP Bomb Activate

The bomb bringing down the core

Egress is normally granted via locked grates surrounding the Core or through an elevator in Geothermal Control. However, the lower area of the latter has been flooded since shortly after the start of the Rapture Civil War. Jack must drain the area using redirected magma pipes to boil off the water. He then can use Kyburz' completed EMP Bomb to overload the Core, stopping the energy flow to the power facilities security systems and allowing him access to Rapture Central Control.

New Discoveries[]

Single Use Events[]

  • There is one Power to the People machine across from the Gatherer's Garden, on the southwest corner of the Core.

New Plasmids and Tonics (Found)[]

  • Shorten Alarms 2 - Next to a corpse after taking the elevator in Geothermal Control, just prior to entering the Core.

Audio Diaries[]

  1. Bill McDonagh - Fontaine's Legacy - Hephaestus Core near the Vita-Chamber.
  2. Anya Andersdotter - Assassin - Hephaestus Core near the Gatherer's Garden.
  3. Andrew Ryan - Impossible Anywhere Else - Hephaestus Core on the desk in the bottom walkway.



  1. Anya Andersdotter's Audio Diary: Going to Heat Loss