There is also a high cost to get something into space, a risk of it blowing up or crashing while heading to space, dealing with very, very long wires (space is

There is also a high cost to get something into space, a risk of it blowing up or crashing while heading to space, dealing with very, very long wires (space is ~160km-2,000km) as opposed to the 50 and 200 meters that'd be used for servers under the water. Also is the issue of having these very long cables running through airspace. Airplanes would have to be made aware of these wires. I can also imagine a lot less electromagnetic interference going on under the water. Also, heat transfer becomes more difficult. No longer is there conduction of hot metal to cold water. In space, you have one main option for transferring heat. Radiation. I think this is addressed in your edit, but yeah, there's the Sun adding energy while you're struggling to radiate out your own server heat...