The Crimson Cavern sits behind a sealed red gate inside the Luminescent Cavern. Access is granted only after you present a Crimson‑mutated Colossal Blue Dragon to the Crimson Guard. Once the gate opens, an underwater tunnel leads to the cavern, so plan for oxygen management using diving gear or a water bubble.

Unlock Crimson Cavern in Fisch (requirements and overview)

To reach Crimson Cavern, you must first have the Luminescent Cavern open, then obtain a Colossal Blue Dragon and roll it to the Crimson mutation via the appraiser. Hand that Crimson Colossal Blue Dragon to the Crimson Guard posted at the red door to have the gate removed. You do not need to finish the Luminescent Cavern bestiary to unlock this door.

Luminescent Cavern entrance (GPS). 1013, -313, -4038.
Crimson Guard NPC (GPS). -1019, -336, -4332.
Crimson Cavern (GPS). -1035, -360, -4800.
Key requirement. Submit a Crimson‑mutated Colossal Blue Dragon to the Crimson Guard.
Access note. Bring diving gear or a water bubble to traverse the underwater tunnel safely.

Unlock Crimson Cavern in Fisch (step‑by‑step)

Step 1: Open the Luminescent Cavern by submitting the required keystones at the Mysterious Crack in Desolate Deep. If you need a bearing, the entrance sits near 1013, -313, -4038.

Step 2: Enter the Luminescent Cavern and move toward the waterfall area. This is the primary spawn zone you’ll use for the next step.

Step 3: Catch a Colossal Blue Dragon. It is an exotic, time‑limited spawn that appears for roughly 15 minutes. Clear weather, Spring or Summer, and Shark Head bait improve your odds.

Step 4: Use a Sundial Totem to prompt an earlier Colossal Blue Dragon spawn if you don’t want to wait on the natural timer. Stock a few totems to repeat attempts efficiently.

Step 5: Appraise your Colossal Blue Dragon at Moosewood until it rolls the Crimson mutation. While Crimson fish can be caught using the Scarlet Spincaster, that rod is only obtainable inside Crimson Cavern—so appraisal is the practical route.

Step 6: Travel to the Crimson Guard posted at the red gate inside the Luminescent Cavern. Head to approximately -1019, -336, -4332.

Step 7: Submit the Crimson Colossal Blue Dragon to the Crimson Guard. The red gate will be removed once the turn‑in is complete.

Step 8: Equip your diving gear or activate a water bubble before proceeding. The access tunnel is submerged; without oxygen support, you will drown en route.

Step 9: Swim through the underwater tunnel to reach the Crimson Cavern proper. The cavern’s general GPS is -1035, -360, -4800.

After unlocking: starter setup for the Crimson Cavern bestiary

If you plan to complete the Crimson Cavern bestiary, a strong all‑round option is the Ethereal Prism Rod paired with Night Shrimp or Weird Algae. This setup improves hookup consistency and reduces time between successful catches across the pool of species found there.

With the Crimson gate open and your oxygen handled, you can reach the cavern reliably and start working on its exclusive catches and rods. Keep your mutated dragon hand‑in ready and you’ll only have to do the unlock once.