The Nano-suit was created by Superman to use when his pursuits would take him to space or in water for when he go to explore or study.
When Superman planned to go to space on the Krypton, he created a suit for this endeavor. It is made out of nano-bots stored in a small compartment in Superman's buckle that coats and integrated with Superman's uniform, turning the blue and red into a single shade of silver, the crest of the House of El into a white "S" in a silver diamond outlined in white; the boots are turned white, and formed gloves as they coated his hands; his cape went silver as the nano-bots coated it. The suit comes with a helmet that provides a heads-up display.
The suit would also later to be used in protecting Superman from being exposed to Kryptonite radiation.