Games like The Abyss Below
Games like The Abyss Below include Iron Lung, Subnautica 2, Subnautica, Outer Wilds, and Lethal Company. We matched them by the tags players give The Abyss Below on Steam (Exploration, Underwater, Submarine, 3D, and Simulation): closest matches first, and among equally close ones the better-known games.

Iron Lung
Shared: Submarine · Underwater · Horror

Subnautica 2
Shared: Underwater · Exploration · Horror

Subnautica
Shared: Underwater · Exploration · Horror

Outer Wilds
Shared: Exploration · Adventure · Mystery

Lethal Company
Shared: Exploration · First-Person · Horror

Firewatch
Shared: Adventure · Exploration · First-Person

SOMA
Shared: Exploration · Horror · Psychological Horror

Escape the Backrooms
Shared: Horror · Exploration · First-Person

What Remains of Edith Finch
Shared: Exploration · First-Person · Adventure

Inside the Backrooms
Shared: Horror · Exploration · Psychological Horror

MOLE
Shared: Simulation · Adventure · Horror

MiSide
Shared: Psychological Horror · First-Person · 3D

PEAK
Shared: Exploration · Adventure · First-Person

DREDGE
Shared: Exploration · Adventure · Mystery

Subnautica: Below Zero
Shared: Underwater · Exploration · Horror

Scanner Sombre
Shared: Exploration · Horror · First-Person

Amanda the Adventurer
Shared: First-Person · Horror · Adventure

Rental
Shared: Exploration · Horror · Adventure

Still Wakes the Deep
Shared: Horror · First-Person · Psychological Horror

Bad Parenting 1: Mr. Red Face
Shared: Adventure · Exploration · Horror

Five Nights at Freddy's: Secret of the Mimic
Shared: First-Person · Exploration · Horror

The Exit 8
Shared: Exploration · Horror · 3D

A Game About Digging A Hole
Shared: Exploration · Simulation · Horror

Layers of Fear (2016)
Shared: Horror · First-Person · Psychological Horror