CO2 near Venus' surface is a supercritical fluid, which is neither gas nor liquid, but has properties of both. At present, the CO2 is more gas-like, but in the past Venus' surface pressure may have been even higher, possibly enough to support a more liquid-like supercritical CO2 (Bolmatov et al., 2014).

There is also supercritical CO2 within Earth's crust. Supercritical and even actual liquid CO2 are released by hydrothermal vents on the sea floor.