If you’ve been grinding through the Moontide Sea expansion in 2026, you’ve probably stumbled across that ominous curved facility looming off the northern isle. I sure did – and for the longest time, I had no idea how to get inside. Turns out, the key is a quest called Beneath the Lunar Sea, and completing it is 100% necessary to unlock the Curtain-Form Blackbody Containment Lab. That’s where you’ll dump all those Luna Sigils you’ve been hoarding for Primogems, Acquaint Fate, and the shiny new Luna Treasure Compass. I finally cracked it after a few facepalm moments, so let me walk you through exactly what I did.

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First things first: how to even start the quest

Before you can do anything, you need to have finished the main story up to the Moontide Sea chapter. That’s a given by now if you’re in patch 5.8 or later. Once that’s done, make your way to the small island directly north of the lab. On your map, it’s that weird crescent-shaped building with a locked door. On the island, you’ll spot a scared Kuuhenki – yes, that floating jellyfish creature – trembling in place. That’s your quest giver. But it won’t speak to you until you deal with the aggressive sphere enemy hovering nearby. Smack that thing into oblivion, and the Kuuhenki will calm down and lead you right to the entrance of the facility. The quest Beneath the Lunar Sea will pop up on your screen, and the locked door will now be interactable. Easy peasy so far, right? I got stuck for a solid ten minutes because I approached the door first and wondered why nothing happened.

The real puzzle: navigating the facility interior

Once you step inside, it’s puzzle time. Don’t worry, it’s not as confusing as it looks – just a series of very specific interactions. Here’s exactly what I did, step by step.

  1. Push the Ancient Moon Pearl – Right near the entrance, there’s a giant glowing pearl. Push it toward the Pearl Power Station on the wall. This opens the first door.

  2. Drop down and absorb energy – Go through the door and take a leap of faith down to a lower chamber where Moon Energy Pearls are scattered. Look for the glowing Archaeolume Energy spots and absorb them. You’ll need that energy to do anything else.

  3. Glide to the northern platform – With the energy in you, glide over to the platform on the north side. There’s a middle door here; walk past it and turn left. You’ll spot a cracked wall that you can break by just walking into it. No joke, I danced around this area for ages before I realized it was destructible.

  4. Free the jellyfish – Inside the hidden room, a few mobs are harassing a trapped jellyfish. Clear them out and the poor thing will thank you (well, it pulses happily, which is basically the same).

  5. Power the generator – Reabsorb the nearby Archaeolume Energy, then shoot Ripples (that charged ability you have) at the Back-Up Power Generator. This turns on some lights and activates a nearby lift. Aim carefully – I missed twice and had to recharge.

  6. The stacked stones trick – Right next to the jellyfish, there’s a pile of stones. Aim another Ripple at those stones while you’re still glowing with Archaeolume Energy. The lift will activate, and you’ll get a Material Storage Chest. Opening it spawns a Moon Pearl Launcher. This is the gadget you’ll be best friends with for the next two minutes.

Mastering the launcher mechanic

Now the fun part. Stand next to the launcher and absorb Archaeolume Energy again. Step onto the launcher and jump – it’ll fling you upward. While you’re in the air, quickly aim your Ripple shot at the Archaeolume Energy Barrier in the ceiling directly above the launcher. If you hit it, a hole opens up and a few Ancient Moon Pearls will rain down like celestial bowling balls. I missed the shot on my first attempt and fell down hilariously, so make sure you’re right above the launcher when you jump.

Once a pearl drops, push it onto the launcher and interact to launch it toward the Pearl Power Station near the previously locked door. Here’s the tricky part: you need to follow the pearl and roll it into the empty slot of the Power Station. It’s a bit like herding an oversized marble, but the path is fairly linear. If the pearl gets stuck, just give it another push from the side.

The final reveal and rewards

When you slot that final pearl into place, the door behind you hisses open. Inside, you’ll find the heart of the facility – the Containment Lab tree. It’s this gorgeous, bioluminescent plant-like structure. Interact with the Terminal next to it, and the quest completes. You’ve now officially unlocked the Curtain-Form Blackbody Containment Lab.

From here on out, any Luna Sigils you collect across Moontide Sea, the Dark Side of the Moon, and the Dunnana Forward Station can be exchanged right at this Terminal. The reward tiers are super satisfying:

Reward Tier Required Sigils Notable Prizes
Level 1 10 60 Primogems, 3 Hero's Wit
Level 2 25 Acquaint Fate ×2, Mora
Level 3 45 Luna Treasure Compass, 100 Primogems
Max Level 70+ Exclusive namecard, Intertwined Fate ×2

Obviously, you want to max out the lab. Each region drops a limited number of sigils per week, so I’ve been hopping between Moontide Sea and the Dunnana Forward Station daily to grab respawns. The compass makes life so much easier because it pings nearby sigils on the minimap. At max level, the namecard you get is stunning – a dark blue nebula with a golden crescent. Totally worth the grind.

A few tips from my own failures

  • Don’t leave without recharging: The Archaeolume Energy buff doesn’t last forever. If you lose it mid-puzzle, you’ll have to backtrack to the nearest energy node. I did this three times because I got distracted.

  • Mark your energy spots: There are a couple of energy clusters in the room with the cracked wall. Place a map pin there so you don’t wander aimlessly when your glow disappears.

  • The launcher angle matters: Stand in the dead center of the launcher when you jump. If you’re even slightly off, your Ripple shot will clip the edge of the barrier and you’ll have to wait for more pearls.

  • Co-op can help (or not): You can do this entire quest in co-op, but only the host gets quest progress. I tried helping a friend and ended up doing the pearl-launching step six times because we kept messing up the timing. Bring a bow character for easier aiming.

By the time you finish, you’ll feel like a certified puzzle ninja. The satisfaction of slotting that last pearl and seeing the tree light up? Unmatched. Now go spend those Primogems – the current banner isn’t going to wait forever, and that Luna Treasure Compass is absolutely worth the short questline. If you’re still working on reaching the outer space part of Moontide Sea, I’d recommend tackling that first so you can grab even more sigils right after unlocking the lab. Happy exploring, Traveler!