A volcano is a large opening in the earth's crust from which erupt magma and ash. The coolest volcanos for me are: the tallest, the widest, and the most active.
Ojos Del Saldo is currently the tallest active volcano on earth. It is exactly 22,615 ft tall. It can be found in the Andes mountains in Argentina.
Kilauea is the world's most active volcano; it is located in Hawaii. Since the Europeans arrived in Hawaii it erupted 62 times in 245 years, that is 1 eruption every 3 to 95 years.
Two years ago, I visited Vesuvius, an active volcano in Italy. Its most famous eruption was the time it wiped out Pompeii in 79 AD. Pompeii was a Roman city located near Mount Vesuvius.
Tamu Massif is the largest volcano in the world; it is an extinct undersea volcano which is off the coast of Japan in the Pacific Ocean. It is about the size of Poland or Italy.