Nea Kameni Volcano
Basically, you can visit all day, but it is not recommended to go at night, because the light is not good, it is easy to be dangerous. (Local time)
The Carmeni volcano erupted several times and gradually became a volcanic island emerging from the seabed volcano. Now the volcano is in a dormant period and safer, and the visit to the crater has become an important tourist attraction in Santorini. Every day in the summer, ships sail from Santorini to the volcanic island.