Kilauea's Sulphur Vents

There are four features active in Volcano National Park:

1) a lake of lava in the active caldera
2) surface lava oozing slowly across a plain
3) groundwater that is heated to steam and vented
4) sulphur vents

This last one is pictured.  It shows volcanic gasses (plus a bit of steam from groundwater) precipitating native sulphur at the vent opening.  Unlike regular steam vents, the sulphur is evidence of a channel from here all the way down to the magma.