Roblox Fisch: How to Unlock the Obsidian Trench

The Obsidian Trench is the newest layer buried under Mariana’s Veil in Fisch, and it is not somewhere you can simply sail to. Access is account progression: a long questline called Mariana’s Awakening that drags you back through every existing Veil layer, hands you five gauntlets, and ends with a randomized riddle you solve by catching one very specific fish.

Quick answer: Talk to Vaelor at Roslit Bay, complete all five descendant quests for their gauntlets, perfect catch a Scylla, then hold the riddle’s mutated Scylla at the Obsidian Pocket gate.

Step 1: Starting at Roslit Bay — The unlock order runs from Vaelor at Roslit Bay through Ignis, Glacius, Tenebris, Luminis and Resonus. Shown at 01:17 in SpaceQT’s video. Image: Aliluma

What you need before starting Mariana’s Awakening

Every descendant quest is locked to its own layer and its own rod, so there is no shortcut around the old progression. Check you have the following before you leave Roslit Bay.

All five original Mariana’s Veil layers unlocked and reachable.
The layer rods: Volcanic Rod, Challenger’s Rod, Rod of the Zenith, Ethereal Prism Rod and Leviathan’s Fang Rod.
Bait for the new species, including Worm, Squid, Shrimp, Fish Head and Seaweed.
Anything that boosts mutation odds, such as the Mutated Sharky companion or a Glitched potion.

Several of the required fish are locked to a season, time of day and weather combination, so expect to wait out a few in-game cycles rather than grinding them all in one sitting.

Step 1: Start the questline with Vaelor at Roslit Bay

Head to Roslit Bay and find Vaelor standing near the palm trees with a quest marker above his head. Talking to him gives you Worthy of the Abyss, the quest that frames everything else.

Read the quest log. It lists five objectives — satisfy Ignis, Glacius, Tenebris, Luminis and Resonus — one for each layer of Mariana’s Veil, tied to the glowing mineral veins Vaelor asks you to investigate.

Quest log display — The Worthy of the Abyss quest log tracks all five descendants at once. Shown at 00:11 in FyReO’s video. Image: Aliluma

Use the Traveler’s Whistle to move between layers. The order does not matter, but each descendant only accepts catches made with their layer’s rod, so fish one layer at a time.

Step 2: Complete the five descendant quests for their gauntlets

Each of Vaelor’s descendants guards one layer and asks for mutated versions of the new fish added across Mariana’s Veil. Finishing a task awards that layer’s gauntlet, and you need the full set.

Descendant	Layer	Rod	Reward
Ignis	Volcanic Vents	Volcanic Rod	Volcanic Gauntlets
Glacius	Challenger’s Deep	Challenger’s Rod	Challenger’s Gauntlets
Tenebris	Abyssal Zenith	Rod of the Zenith	Abyssal Gauntlets
Luminis	Calm Zone	Ethereal Prism Rod	Calm Gauntlets
Resonus	Veil of the Forsaken	Leviathan’s Fang Rod	Veiled Gauntlets

Ignis stands opposite the Volcanic Rod at roughly (-3343, -2028, 4076). Glacius sits across from the Challenger’s Deep rod at (738, -3355, -1529). Tenebris is on the third level of the Veil at (-1043.4, -1043.7, 84.7), across the anglerfish pond — glide over rather than swimming through it.

Required catches for each descendant

Ignis: perfect catch 2 Ashen Fortune Charred Coelacanth and catch 1 Ashen Fortune Obsidian-Plated Piranha.
Glacius: catch 3 Chilled Hoarfrost Halibut and perfect catch 1 Chilled Glacial Gulper.
Tenebris: catch 2 Wrath Lumin-Lure Lanternfish and perfect catch 1 Wrath Void-Drifter Jelly.
Luminis: Land 2 Pearl-Plated Pleco plus 4 Geode Grouper.
Resonus: catch 5 Gargoyle Goby and 3 Wraith-Whisper Ray.

Bait, time and weather for the mutation fish

Fish	Bait	Time	Weather
Obsidian-Plated Piranha	Worm	Day (Summer)	Rain
Charred Coelacanth	Squid	Night (Summer, Autumn)	Clear
Glacial Gulper	Shrimp	Night (Winter)	Foggy
Hoarfrost Halibut	Fish Head	Day (Winter)	Clear
Lumin-Lure Lanternfish	Shrimp	Night (Spring, Autumn)	Clear
Void-Drifter Jelly	Seaweed	Night (Autumn, Winter)	Foggy

Turn the fish in to the descendant who asked for them and the matching gauntlet lands in your inventory. You can open your bag at any point to see how many of the set you are holding.

Inventory screen — The inventory screen with the collected gauntlets, including the Mariana's Gauntlets awarded at the gate. Shown at 01:52 in FyReO’s video. Image: Aliluma

Step 3: Perfect catch a Scylla and jump into the void

Return to Vaelor at Roslit Bay and hand in Worthy of the Abyss. He follows it with a single task — land a Perfect Catch on a Scylla.

Travel to the Veil of the Forsaken and fish for Scylla. Its preferred bait is Shark Head, and a Perfect Catch is the only result that counts, so drink your usual luck and control potions first.

Once the Scylla is reeled in, jump straight into the whirlpool where you caught it. You drop through the void and land in the Obsidian Pocket, a small holding area that gets marked as discovered.

Step 4: Solve the gate riddle with a mutated Scylla

Inside the Obsidian Pocket is a sealed gate — the Crevice Wall — with coloured lights above it and a riddle carved into the floor. The riddle is randomized per player and points at one layer’s gem, which is why copying someone else’s answer does not work.

Read the riddle at the gate, then teleport back to Roslit Bay and talk to Vaelor again. Ask him for a clearer hint and he spells out exactly which rod, mutation and fish your version needs, for example a Chilled Scylla caught with the Challenger’s Rod.

Equip the rod he named and go back to the Veil of the Forsaken. Enchantments such as Piercing or Overclocked and the matching gauntlet help push the mutation through on the Scylla you hook.

With the mutated Scylla in hand, jump into the void again and walk up to the gate. Holding the fish lights the coloured pedestals, ignites the layer gems and opens the Abyss Gate.

Step 3: Unlocking the Abyss Gate — Igniting the layer gems at the wall is what opens the Abyss Gate route into the trench. Shown at 02:18 in SpaceQT’s video. Image: Aliluma

How to confirm the Obsidian Trench is unlocked

You know it worked when the pedestal lights all activate, the central passage slides open and you drop down into a dark, crystal-lined cavern. The game registers Obsidian Trench as a newly discovered location, and the Mariana’s Gauntlets are added on top of the five layer gauntlets you already carry. From that point the trench is a normal travel destination on your whistle.

Entering Obsidian Trench — The passage opens into the Obsidian Trench, where the rod shop sits behind a 100 percent bestiary requirement. Shown at 01:59 in Danz’s video. Image: Aliluma

Trench Suppression and what to do first inside

Stepping into the trench applies Trench Suppression, an environmental debuff that can gut your rod stats by up to 90 percent. Glowing white crystals are scattered around the area, and interacting with one purges most of the penalty — enough to drop the effect back to around 5 percent — so clearing crystals is part of routine fishing here, not an optional secret.

Managing Suppression Debuff — Interacting with a glowing white crystal pulls the Suppression penalty back down. Shown at 02:18 in Danz’s video. Image: Aliluma

The trench holds its own 12-entry bestiary, with 10 named species and two hidden catches still unidentified. The shop NPC down there sells the Chasm-Stalker Rod for 5,000,000 C$, gated behind 100 percent Obsidian Trench bestiary completion and the Skolopendra boss, so the unlock you just finished is the start of the grind rather than the end of it.