The Unfathom is a late-game location at the bottom of the ocean from Another Crab's Treasure. When Krill find themselves down there, it will be hard to see your claw in front of your face. To get a better look around, you should take the very flawed lighted sneaker.
Once you fall into the Unfathom, there will be some light from the surrounding glow sticks, but it will still be incredibly dark down there. My first time traversing this sunless area, I did not find the glowing Lanternfish, which makes traversing the depths much more difficult.
Lanternfish stowaway location in Another Crab's Treasure
To light your way, you'll need to pick up the Stealth Lanternfish. It will be located in a Styrofoam castle container in this part of the Unfathom. It's near the wreckage of the pirate-themed pinball machine, near where you meet up with the professor again. It will be a shiny red object inside the Styrofoam container.
Related: Where to get Microplastics in Another Crab's Treasure
To use the Lanternfish pet in Another Crab's Treasure, you must replace one of the two Stowaway slots in the menu with the Lanternfish. This black, glowing fish will then light up your surroundings and keep you company on your journey.
If you face the fish, you can even stroke it; just look for the button to appear on the screen. On the Switch it was the X button. You will need 30 Vitality to equip him, so you may need to go back to the Lunar Conch in the area to level yours until the Lanternfish can be equipped.
For more Another Crab's Treasure, check out Best Adaptations in Another Crab's Treasure on Pro Game Guides.
