Hi All In Hal Clement's book "Noise" there's a planet with an ocean 2,900 kilometres deep. Radius of the planet is 1.15 Earth, surface gravity 1/3 Earth's, and thus the planet's mass is 0.44 Earths. The deep, deep parts of the ocean are close to the core and hot enough to be supercritical - but being under 80,000 bars of pressure the supercritical fluid is as dense as water or close to. My question is whether the planet can avoid the ocean water turning into Ice VII deep down past the Ice VI/VII/liquid triple-point at 22,000 bar. So just how compressible is water and how does that vary with temperature? I have physical property tables to 1000 bar and 800 C, so my data runs out past that pretty quickly. A gas adiabat I can figure out, but how does one do so for a liquid? For a supercritical fluid?