Preheat oven to 300° F.
In a medium saucepan over medium to medium-high heat, stir together water, sugar, and peanuts. Bring to a boil. Boil, stirring regularly, until water is absorbed. It will turn from a syrupy consistency to a grainy sugar consistency.
Spread peanuts out onto a rimmed 11″ x 17″ pan, breaking up any large pieces of peanuts that have clumped together. Sprinkle with sea salt.
Bake for 20 to 25 minutes for a lighter coating and crunch, or 30 minutes for a deeper darker coating, stirring after the first 15 minutes. Let cool on pan. Store in an airtight container at cool room temperature once completely cooled.
