Sunrise at the summit of Gunung Batur volcano in Bali (Indonesia)

The fumaroles are steam (i.e. water).

The shelter at the summit is a tea house, and the woman who works there has found clever ways to capture in pots the water from condensation of the steam fumaroles, so she can make tea without having to haul the water up the steep trail every morning.

The hike to the summit is only a couple of hours and can be easily done with no guide. Sunrise at the summit is very scenic, so a pre-dawn (night) start is advised.

For more information about Mount Batur, read en.wikipedia.org/wiki/Mount_Batur