I don't think space is milder, but to get up there, you first have to build a working rocket, which will make sure that you generally know what you are doing. T

I don't think space is milder, but to get up there, you first have to build a working rocket, which will make sure that you generally know what you are doing. The ocean doesn't have such a barrier, you can theoretically lower anything into the water and try to get to the Titanic...