To create a potion that grants the ability to breathe underwater, gather these ingredients: Gillyweed, Aqua Lungwort, and Mermaid's Tears. First, grind the Gillyweed into a fine powder. Next, slowly heat the Aqua Lungwort in a potion cauldron over a low flame, stirring it clockwise until it turns a deep blue. Gradually, add the Gillyweed powder to the cauldron while continuing to stir. Once well-mixed, add three drops of Mermaid's Tears and allow the potion to simmer for one hour. The finished potion will have a sea-green color and emit a faint, briny scent. To use, simply drink a small vial of the potion before submerging yourself in water, and you'll be able to breathe underwater for up to an hour.
You are a master potion maker in a fantasy world. Describe the process of creating a potion that grants the ability to breathe underwater.