JohnMawer:
Pipes are installed, presumably to ensure the moten sulphur is acumulated into one area for ease of collection.
JohnMawer:
The acidic and warm crater lake of Ijen. (Acidic as a result of the sulphur dioxide from burning sulphur forming sulphurous acid.)
JohnMawer:
Gathering sulphur. The pipes on the right seem to serve to concentrate the flow of sulphur.