Largest volcano on earth

Measured from its base, the tallest would be Mauna Kea in Hawaii, which like the adjacent Mauna Loa has a deep seafloor base on the Hawaiian hotspot.

But the highest above sea level is the Nevado Ojos del Salado ("snow-covered salty eyes"), a stratovolcano in the Andes mountains, about 600 km (370 miles) north of Aconcagua, the highest mountain in the Americas. Ojos de Salado is 6893 meters (22,615 ft) in height. However, it has not been active since approximately 700 AD.