A planet orbiting a K-type orange dwarf star, significantly cooler than Earth. Its atmosphere is rich in nitrogen and carbon dioxide, with a lower oxygen content, leading to a denser, greenhouse-warmed atmosphere despite the cooler star. Liquid water exists primarily in subsurface oceans kept liquid by geothermal activity, with only small, ephemeral surface lakes and rivers in equatorial regions. Dominant habitat is subterranean, within vast cave systems and ocean trenches.