you are right that I am extrapolating off of the water density chart I posted, and even so poorly.

Goes from 1000 to 1080 kg/m³ over 200 Mpa, by the time you get to 1000Mpa it would be 1400 kg/m³ and the nearly equivalent air temperature goes to around 1150 kg/m³

The log plot threw me off. This would be even worse for salt water since it is more dense than pure water which is the chart I have.