I think water is rather rare as a coolant these days. Organics (chemical sense not farming sense) like propylene glycol or some kind of glyme aren't potentially corrosive to metals if spilled, are harder to grow shit in, have lower volatility, and have a higher thermal limit. Maybe also with a little bit of antifouling agent thrown in. My main gripe with them is that if you do spill them, they don't evaporate and you're slipping over the floor for the next few days because you missed a spot.

But yeah, air cooling ftw