You can see (and smell) lots of sulfur dioxide gas and steam coming out of vents at Volcanoes National Park.
Volcanoes National Park, Hawaii: Lava Tubes, Rainforests and Volcanoes
Kilauea volcano’s summit caldera in 4K video
You can see lots of sulfur dioxide gas coming out of the summit crater / caldera of the Kilauea volcano. The camera’s zoom allowed me to get a really close view in 4K video.
Adventures for two 