Preheat oven to 300 degrees. Place a large, ungreased or silicone-lined baking sheet next to the stove top.
In a medium saucepan, combine sugar, salt and water. Place over medium heat and stir until sugar dissolves.
Add peanuts and continue to cook, stirring constantly, until the peanuts are completely coated and no sugar syrup remains, approximately 20 to 30 minutes. The transition from syrup to a "dry" coating will happen very quickly, almost instantaneously, so don't look away and keep stirring.
As soon as the syrup dries out, pour the peanuts onto the cookie sheet and quickly spread them out, separating any large clusters.
Bake the peanuts for 30 minutes; stirring every 10 minutes.
Remove from oven and allow peanuts to cool on the baking sheet. Store in an airtight container.