How to Restore All 4 Sector Towers in Fisch: The Deep

Restoring the four Sector Towers is the backbone of The Deep main questline in Fisch. Each tower needs a specific crafted core, and every core comes from a different NPC scattered across the underwater region. Once all four are lit, the area becomes far easier to explore, and the questline opens up to its next stage.

Quick answer: Start at Chief Engineer Nereus (Main Quest NPC) in Deep City, then hand in materials to Hunter Dan for the Hydro-Core (1P-1), The Cartographer for the Abyssal Lens (1P-2), Dr. Vane for the Bioluminescent Battery (1P-3), and Sledge for Reinforced Housing (1P-4). Insert each core into its matching tower, then return to Nereus to finish.

What restoring the Sector Towers does

There are five beacon towers in The Deep, and the main quest asks you to bring four of them back online. Activating a tower permanently lights up its sector, which improves visibility in that part of the map. It also makes the Roaming Fish in that area more docile, so moving through the region becomes safer over time.

Completing all four turn-ins and installations lets you return to Chief Engineer Nereus to close out the objectives and unlock the follow-up quest, The Master Relay.

Tower coordinates and required cores

Each beacon has a fixed location and a single item requirement. Use the coordinates to find each tower after you have crafted its core.

Tower	Coordinates	Required core	NPC
Beacon 1P-1	-515, -2015, -12050	Hydro-Core	Hunter Dan
Beacon 1P-2	515, -2035, -13215	Abyssal Lens	The Cartographer
Beacon 1P-3	-30, -2330, -12780	Bioluminescent Battery	Dr. Vane
Beacon 1P-4	1620, -2495, -11940	Reinforced Housing	Sledge

Note: The fifth tower, Beacon 1P-5 (1180, -2115, -12080), has no item requirement and sits outside this four-tower objective.

Restore Beacon 1P-1 with the Hydro-Core

Open the quest book and speak to Chief Engineer Nereus, the Main Quest NPC, in Deep City. This starts The Deep main quest for restoring the towers.

Using the on-screen Interact prompt on Chief Engineer Nereus to begin the Sector Tower questline in Fisch. Shown at 00:25 in Danz’s video.

From the central Deep City building, head toward the southeast to find the first pillar and the NPC by the tents. Talk to Hunter Dan to pick up the Restoring 1P-1 objective.

Gather the materials Hunter Dan asks for. Catch drops carry these, for example Chitin Plates from Pistol Shrimp. Hand the items in to receive the Hydro-Core.

The fishing inventory menu, where you sort catches and check the materials needed for each turn-in. Shown at 00:46 in Danz’s video.

Take the Hydro-Core to Sector Tower 1P-1 and insert it. The beacon activates and its sector lights up.

Restore Beacon 1P-2 with the Abyssal Lens

From the first tower, glide to the northwest. Look for an underwater dome, which marks the location of The Cartographer.

Talk to The Cartographer to accept Restoring 1P-2, then craft the Abyssal Lens using the materials requested.

Insert the Abyssal Lens into Sector Tower 1P-2 to bring the second beacon online.

Restore Beacon 1P-3 with the Bioluminescent Battery

Return to Chief Engineer Nereus as your reference point, then head north into the subterranean chamber in the Outer Deep zone. Swim past the glowing mushrooms to reach the scientist.

Returning to Chief Engineer Nereus, the central landmark for tracking down the next tower. Shown at 01:14 in Danz’s video.

Speak to Dr. Vane and turn in the materials for Restoring 1P-3 to synthesize the Bioluminescent Battery.

Install the Bioluminescent Battery into Sector Tower 1P-3 to activate the third beacon.

Restore Beacon 1P-4 with Reinforced Housing

Exit the back of the central building and travel to the southwest. Pass under the archway to find the blacksmith NPC, Sledge, near a shipwreck.

Closing in on the quest marker for the fourth tower, shown at 15m in the gameplay view. Shown at 01:47 in Danz’s video.

Turn in the items Sledge requests for Restoring 1P-4 to obtain Reinforced Housing.

Install Reinforced Housing into Sector Tower 1P-4 to activate the fourth and final beacon in this objective.

Confirm completion and unlock the next quest

With all four cores installed, swim back to Chief Engineer Nereus in The Deep. Turning in with him completes the tower objectives and marks the questline as finished.

Chief Engineer Nereus highlighted as the Main Quest NPC, the final hand-in for the four towers. Shown at 02:14 in Danz’s video.

You will know it worked when the quest updates at Nereus and the next objective, The Master Relay, becomes available. That follow-up sends you to gather the remaining materials and interact with the large master pillar, which rewards the Deep Survey Device MK II. If the tower turn-in does not register, check that you actually inserted the core into its matching tower rather than only crafting it, since each beacon only accepts its own item.