What is the largest volcano in the Solar System?

The largest volcano in the Solar System is Olympus Mons, located on Mars. It stands about 21.9 kilometres (13.6 miles) high, making it nearly three times the height of Mount Everest. Olympus Mons has a base diameter of approximately 600 kilometres (373 miles), which is comparable to the size of the state of Arizona. It is a shield volcano, characterised by its broad, gently sloping shape formed by repeated lava flows. The lack of tectonic plate movement on Mars allowed the volcano to grow to such an immense size over millions of years.