In a small bowl, add the melted butter to the graham cracker crumbs and, using a fork, mix well. You want every crumb coated in the butter as this will be the glue that holds it together.
Pour the graham cracker crumbs into a 9 inch pie dish. Pat them flat with your hand and then use a kitchen glass to press flatter. Start at the center and work out to and up the sides. Set aside.
In a large saucepan over low heat, add sugar, cornstarch, and salt. Slowly drizzle in water, whisking constantly until smooth.
Add half of the blueberries. Bring the mixture to a boil and continue cooking until thickened (about 2 minutes). Set aside to cool.
Once cooled, fold in remaining blueberries and pour the mixture into the crust.
Place pie in the refrigerator to chill for 2 hours, or until set.
Serve topped with whipped cream.