what is the tallest volcano in the world

The tallest volcano in the world above sea level is Ojos del Salado, on the Chile–Argentina border, standing at about 6,890 meters (approximately 22,600 feet). If you define “tallest” by overall height from base to summit, including submarine base, Tamu Massif (an underwater volcano in the northwest Pacific) is far larger by footprint and volume, but it does not rise above sea level. For Mars, Olympus Mons is the tallest volcano in the solar system, with a height of about 22 kilometers (13.6 miles) above the surrounding terrain. If you’d like, I can break down these figures by definition (above sea level vs. total height from base, Earth vs. other planets) and include sources.