The cooking method that fully submerges food in water heated to 100°C at sea level is boiling.
Boiling occurs when water reaches its boiling point and changes from liquid to vapor throughout the liquid, producing bubbles. At standard atmospheric pressure near sea level, pure water boils at 100°C, or 212°F. The food is surrounded by hot water, allowing heat to transfer efficiently into its interior.
Boiling is used for pasta, potatoes, grains, eggs, and many vegetables. It is different from simmering, which cooks food in liquid kept below a full boil, with smaller and gentler bubbles. Steaming cooks food with water vapor rather than immersing it directly in the water.
The temperature is not always exactly 100°C: atmospheric pressure changes the boiling point. At high altitude, water boils at a lower temperature, so foods may take longer to cook. A pressure cooker raises pressure and allows water to reach a higher temperature.