Regina: Underwater 3rd Energy Reactor

60%
Guide Progress
  1. 1

    The 3rd Energy Facility Docks

    3rd Energy Facility / Docks & StorageDino File 5 (Pteranodon), Key for the Box
    The 3rd Energy Facility docks, before descending to the underwater area.

    Control returns to Regina aboard the docked Patrol Ship. Access the EPS terminal to purchase the Heavy Machine Gun (essential for rapid takedowns):

    • Walk onto the dock walkways. Eliminate surfacing Plesiosaurs with single bursts of machine gun fire.
    • In the Storage Space corner where the truck has crashed, collect Dino File 5 (Pteranodon).
    • Swipe the 3rd Energy Facility Keycard at the card reader beside the brown door.
    • Advance past the small boat containing a locked glowing box and enter the 3rd Energy Control Room.
    • In the control room, pick up Dino File 6 (Mosasaurus) from the central table and take the Key for the Box from the upper desk.
  1. 2

    The Mechanic's ID & Elevator Power Puzzle

    Storage Bridge & Sub-Level Power RoomMechanic's ID Card, Diving Suit
    • Pass through the control room's rear door to reach the storage bridge and search the fallen technician to obtain the Mechanic's ID Card.
    • Backtrack to the small boat at the docks and unlock the glowing box using the Key for the Box to reveal a document containing an access passcode. It's always one of eight fixed 4-digit codes — 2350, 3051, 5420, 5210, 1452, 4015, 0153, or 4521 — randomized per playthrough; whichever one shows on your document is the exact code to enter, no need to solve anything further.
    • Return to the elevator in the 3rd Energy Control Room: swipe the Mechanic's ID Card and enter that passcode.
    • Ride the elevator down to the flooded sub-level and enter the generator chamber:
      • Interact with the power restoration monitor and select Yes.
      • Watch the wall panels: whenever a lamp turns red, immediately strike it with the Stungun to turn it green.
      • Continue maintaining the circuits for approximately two minutes until primary power stabilizes.
    • Climb the platform ladder to the suit locker and inspect the center locker to acquire the Diving Suit.
  1. 3

    Submerged Facility & The Reactor Plug

    Underwater Facility / Circulation ChamberAquagrenade, Reactor Plug, Dino File 7 (Plesiosaur)
    The underwater facility, where movement slows and the loadout switches to the Needle Gun.

    Subsea mechanics take effect: movement is slowed, jump is bound to the jump button, and loadout switches to the Needle Gun (infinite ammo) and Shockwave:

    • Eliminate the two Mosasaurs and jump down through the underwater corridor to reach the safe room.
    • Access the EPS computer and purchase the Aquagrenade (mandatory torpedo weapon).
    • Advance through the lower chambers, clearing Mosasaurs along the ocean floor.
    • Approach the elevated platform supported by a cracked pillar: fire an Aquagrenade to demolish the pillar and jump up to the upper door.
    • Pull the wall lever inside to activate the elevator lift.
    • Cross the pipe bridge, drop onto the lower platform, and inspect the deceased diver to retrieve the Reactor Plug.
    • Return to the first save room, insert the Plug into the central computer, and select Yes to open the 3rd Energy Reactor shutters (collect Dino File 7: Plesiosaurus beside the corpse).
  1. 4

    The Reactor Shutters & City Keycard

    3rd Energy Reactor AccessCity's Keycard
    • Head through the lower double doors, jump over the partially opened security shutter, and ride the small red elevator up to the 2nd floor.
    • Cross the upper bridge, jump down into the south trench, and enter the final underwater save room.
    • Ensure you have at least 6 Aquagrenade torpedoes loaded.
    • Take the red elevator, leap over the open reactor barrier, and collect the City's Keycard lying beside the corpse ahead.
    • Ride the adjacent elevator down into the central reactor arena.
  1. 5

    Boss Battle: Aquatic Plesiosaurus

    Underwater Reactor Core
    • A massive Plesiosaurus blocks the reactor exit passage:

    Plesiosaurus (Underwater Reactor)

    Difficulty

    The colossal aquatic apex predator lurking within the flooded Third Energy reactor chamber.

    The Plesiosaurus that guards the exit of the underwater reactor.
    Attacks
    • Rapid underwater lunges and bite sweeps
    • High-speed perimeter circling before head-on charges
    Strategy
    • Position Regina in the central trench near the northern edge.
    • Wait until the Plesiosaur emerges into view, then immediately fire 2 Aquagrenade torpedoes directly into its head.
    • Reposition across to the opposite end of the trench.
    • When the beast rounds the corner for a second pass, launch 2 more torpedoes to terminate the encounter (earning 10,000 EP).
    • Scale the reactor platforms, activate the elevator console, and ascend to the surface.
    • At the Edward City Front Gate, Regina meets Dylan and unlocks the perimeter gate with the City Keycard. A transmission from David urges the team into the city!

Enjoying the content?

Help keep our guides 100% ad-free and support future game additions.

Buy me a coffee
Buy me a coffee