Line a baking sheet with parchment paper. Set aside. In a large pot, whisk together the sugar, corn syrup, and water over medium-high heat. Bring to a boil.
Add the peanuts, stir, and continue boiling the mixture until the temperature reaches 300 degrees F. (You'll want to use a candy thermometer to check the temp.)
Remove from the heat. Add the butter and vanilla extract and stir to combine. Finally, quickly stir in the baking soda. The mixture will froth up and rapidly increase in size.
Transfer the peanut brittle mixture to the prepared baking sheet and quickly spread it into an even layer. Allow it to cool completely, about 1 hour.
Use the back of a wooden spoon to break the brittle into pieces. Store in an airtight container on the counter.
Notes
Nutritional information is an estimate. The brittle will break into pieces of various sizes that are not uniform.