Blowing sky high is a common phrase that refers to something that is exploding or being destroyed. The antonyms for this phrase would be words that describe the opposite of an explosion or destruction, such as settling down, calming down, or being peaceful. These words would indicate a state of tranquility or stability, where everything is under control and there are no fears of any kind of disturbance. Some appropriate antonyms for blowing sky high could be settling, calming, peaceful, or even stagnant, depending on the context in which the phrase is used. Therefore, these words would indicate a state of safety and security where no one is in danger or in harm's way.