The planet with the highest mountains in the solar system is Mars. Olympus Mons, the tallest volcano and mountain, stands at approximately 13.6 miles (22 kilometers) high, making it nearly three times the height of Mount Everest, Earth’s highest peak. This colossal shield volcano also spans about 370 miles (600 kilometers) in diameter, featuring a large caldera at its summit. Mars's thin atmosphere contributes to the unique geological features found on the planet, allowing large volcanic structures like Olympus Mons to form over millions of years. The study of these mountains provides insights into the planet’s geological history and volcanic activity.