The planet known for having the largest volcano is Mars, specifically the volcano Olympus Mons. Olympus Mons is an enormous shield volcano that stands about 13.6 miles (22 kilometers) high, which is nearly three times the height of Mount Everest, Earth’s tallest mountain. It spans approximately 370 miles (600 kilometers) in diameter, making it the largest volcano in the solar system. The volcano's size and unique features have intrigued scientists, providing insights into the geological history of Mars, including volcanic activity and the planet's past environmental conditions, which differ markedly from those on Earth.