FATHOM LINES

Water absorbs light. Not evenly. Each wavelength has a different absorption rate. Red light is gone by 10 meters. Orange by 40. Yellow by 100. By the time you hit 200 meters, only blue and violet remain. Below 1,000 meters there is zero natural light.

The formula is I = I₀ × e^(-kd) where k is different for each wavelength and d is depth. This isn't a design choice. A piece at 3,000m physically cannot have warm colors unless it hits a hydrothermal vent.

Two exceptions exist. Bioluminescence (200 to 1,000m) produces blue-green light at 460 to 490nm. Hydrothermal vents (1,000 to 4,000m) are the only source of warm color at depth, where magma meets water at 350°C+.

The ocean has five depth zones. Each one has fundamentally different geology, and the algorithm respects that. You can't get volcanic terrain on the continental shelf because there are no volcanoes there. You can't get chaotic terrain on the abyssal plain because it's the flattest surface on Earth.

Geological personalities aren't random rolls. They're constrained by what's physically possible at each depth. A piece's character is determined by where in the ocean it comes from.

The rarity system follows the same logic. Volcanic pieces are genuinely rare because volcanism only occurs at mid-ocean ridges (1,000 to 4,000m). A minimal piece at shallow depth is rare because shallow water is full of features. Rarity means geological improbability.

At sea level you're at 1 atmosphere. At the bottom of the Mariana Trench, 1,086 atmospheres. The formula is simple: P = ρgh (density × gravity × height). This pressure literally compresses the art. Line spacing tightens. Features get denser. Surface pieces breathe. Hadal pieces are crushed into tight, packed formations.

Temperature drives order versus chaos. Surface water is 20 to 25°C with turbulent currents, tides, and storms. Below the thermocline (200 to 1,000m), temperature drops sharply. Below 1,000m it barely changes. Near-constant 2 to 4°C. The art follows: surface pieces have wild variation in line weight. Deep pieces are more ordered, more geometric. Almost crystalline.

Every piece is a core sample. The seed determines where on the ocean floor you're drilling. The depth determines what forces are acting on what you find.

Every piece runs through the same pipeline. The seed determines the randomness. The depth determines the physics. Together they produce something inevitable.