Vent Boiling Points

Is the boiling point of water the same at the surface of the ocean as it is at 5000 meters? Click on the question marks to find out the boiling point at different depths.

Notice how the deeper you go, the higher the boiling point is. That is because of the increase in pressure. At sea level, the pressure equals one atmosphere, or 14.69 pounds per square inch. But for every 10 meters you dive, the pressure increases by one atmosphere. So if you were to dive to ten meters, the pressure would equal two atmospheres. A hydrothermal vent 2,500 meters deep experiences 250 atmospheres, or 3,672.5 pounds per square inch.

But why does increasing pressure increase the boiling point? Boiling occurs when a liquid becomes a gas. That change requires energy in the form of heat. As pressure goes up, more heat is needed for water molecules to vaporize and boil.

Likewise, lower pressure lowers the boiling point. If you live in areas that are far above sea level, where the pressure is less than one atmosphere, you may have to cook things like pasta and rice longer because the water boils at a lower temperature and doesn’t get hot enough to cook foods as fast as at sea level.

You can figure out the pressure at any depth in the ocean by using this equation:

Pressure = (depth/10) X 14.69 pounds per square inch (psi)

For example, at 4,000 meters, the pressure = 4,000/10 X 14.69 = 5,876 psi