Archives of Nethys

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Infinite Worlds / Marsh

Marsh Worlds

Source Galaxy Exploration Manual pg. 69
Wetlands are common on terrestrial worlds, yet only a rare few planets are covered entirely by this biome. Such planets often have flat topography that’s conducive to supporting standing water and spongy soils, kept inundated either by consistent precipitation, powerful tides that draw water over vast estuaries, or both. On such worlds, even the rare mountain chains are low, creating rain shadows that channel water into low-lying areas while valleys accumulate steep fens. Because of the diverse range of wetlands, a single-biome planet can support countless varieties of life based on the nuances of drainage, elevation, and soil type, with regional boundaries defined by where bog transitions into swamp, lagoon, or river. Conventional continents might not exist, with dry land instead consisting of peat accumulations a hundred feet thick or greater.
While sapient beings might clear and manage vast aquaculture fields, some animals might dam key waterways and create lakes, while others tear game trails through thick swamps that are then used by countless other organisms. Where societies rise, the combination of perishable materials and unstable foundations mean that ruins swiftly disappear. On tectonically active planets covered by peat and other fuel, lava could spark subsurface fires that slowly burn their way across the world, creating smoldering underground hellscapes that burst upward to consume an entire region before dying out, making way for new growth.