In KSP terminology, a biome is a geographic area on the surface of a celestial body typically corresponding with types of geology like mountains or craters.
In real life, biomes are contiguous areas with similar climatic conditions and organism communities. Without organisms, there are no biomes.
The results of science activities often differ when performed in different biomes, and thus provide more opportunities to earn Science Points in Career Mode to research further along the technology tree. In Sandbox, even the text descriptions from experiments are unavailable, rendering biomes unimportant.
Areas belonging to a biome may be geographically separate, but they're not considered different areas. For example, after performing an EVA Report at Kerbin's north polar IceCap biome, performing one from the southern IceCap gives the same results (and Science Points) as if it had been performed a second time in the northern IceCap.
Currently[outdated], only Kerbin and its moons – Mün and Minmus – are fully mapped with biomes. Jool's moon Laythe and the planet Eve have bodies of water and science activities performed in them are stated as being from "Laythe's oceans" and "Eve's oceans". However, this is just the effect of the situation "SrfSplashed" for a splashdown versus the usual "SrfLanded" surface landing.
The planet Kerbin has 9 regular biomes which extend into atmospheric and orbital altitudes. Roughly 60% the surface is Water. Most of the land area is Grasslands and Highlands.
Currently[outdated], Kerbin is the only celestial body that both has water and biomes. Most rivers and smaller bodies of water are the same biome as the ground around them, offering the chance for science in a SrfSplashed situation. Only one of the biomes does not have a water area in any of the places it occurs on Kerbin. Shores, obviously, have both land and water; and small islands in Kerbin's oceanic areas, such as at the Insular Airfield, sometimes are counted as surface landings, not splashdowns, within the Water biome.
Kerbin is also the only celestial body that also has special location biomes: the grounds of KSC and within it the LaunchPad and the Runway. Each of these three count as a distinct biome but only with experiments performed on the surface. The KSC grounds are within a Shores biome, so experiments while flying at any altitude over the LaunchPad, Runway, or KSC count only as Shores. It is difficult but possible to get an "EVA Report while flying over" these three, however the exact trigger is only suspected to relate to split-second timing while jumping on a parked vessel.
Kerbin biome list
The Mun has in total 15 biomes, 7 of which are uniquely named major craters. Most of the surface area belongs to the Midlands biome followed by the Highlands. Canyon biomes extend off a few major craters.
Mun biome list
- Northern Basin
- Highland Craters
- Midland Craters
- East Crater
- East Farside Crater
- Farside Crater
- Northwest Crater
- Southwest Crater
- Twin Craters
- Polar Crater
- Polar Lowlands
Minmus has in total 9 biomes. The most distinctive quality of Minmus's biomes is the variety of Flats, which in-game text describe as "lake beds", that are indeed flat areas which may represent frozen lakes. Roughly two-thirds of the surface area is irregular terrain transitioning between Highlands, Midlands, and Lowlands with Slopes in-between.
Minmus biome list
- Lesser Flats
- Great Flats
- Greater Flats