Aquatic Biome

The Aquatic Biome is a deep, water-heavy biome made up of several small islands and caverns arranged by depth. Its contents change with variant and position within the biome, but it is generally one of the more distinctive terrain types in the game because it mixes flooded areas, frozen pockets, and dry cavities in a single region.

The topmost island usually contains Dirt and Sand. Lower islands can include Sandstone, Mafic Rock, and Oxylite, and some versions add a small Sandstone island with a bit of Algae and possibly an Arbor Tree. Around the Cool Slush Geyser, the surrounding island starts out frozen with Ice and Crushed Ice, but it quickly thaws once the nearby 40–50 °C water spreads in. At the bottom, the biome opens into a large dry cavern filled with Oxygen and Carbon Dioxide rather than water, creating a very different environment from the flooded layers above.

Aquatic Biome variants differ mainly in their temperature and the features they contain. The common base versions are hot and may appear as Frozen, Steamy, Gassy, or Inactive variants. There is also a Frozen variant with much lower temperatures. The biome’s contents can include a Cool Steam Vent and, depending on variant, either a Natural Gas Geyser, a Hydrogen Vent, or a Chlorine Gas Vent, plus ruins in several cases. In the Inactive version, only ruins remain. The biome also has named sub-forms such as Ocean, Surface Island, Center Island, Oxylite Island, Frozen Island, Polluted Water Vent Island, and Core.

The biome does not naturally generate metal ores, gases, plants, or critters in its standard form, which makes its fixed terrain and point-of-interest layout especially important. Some variants also contain a Volcano trait version, and the Volcano Hole and Solid Magma forms include magma-related terrain that cools into Igneous Rock. The Volcano Hole variant contains 5 Volcanoes, while the Volcano variant used by the Volcanoes World Trait contains 8 Volcanoes randomly placed across the map.

A few practical notes make the biome easier to manage:

• The biome is extremely deep, so Atmo Suits are effectively required to work through it safely.
• Reaching the bottom is valuable because the lower dry cavity offers large amounts of gas space.
• The dry lower section can support large-scale gas handling and storage because it contains much more Oxygen and Carbon Dioxide than water.
• The frozen upper areas can melt quickly once exposed to warmer water, so excavation can change the biome’s layout fast.
• In magma-related variants, cooled magma becomes Igneous Rock, which can leave behind useful solid terrain after the heat source is gone.

In game code, the biome is named Magma.