Volcanoes can be found on land and underwater, creating islands. The tallest volcano in the solar system is Olympus Mons on Mars, while Jupiter's moon Io is the most volcanically active body in the solar system. Volcanoes can impact the climate and cause dangerous eruptions that endanger human life through lava, ash, gases, and other hazards. People should seek shelter indoors and move to higher ground if outdoors during an eruption.