|The geothermal plain surrounding Geysir|
The second major attraction on the Golden Circle route is Geysir, the geyser from which all other geysers got their name ("geysir" means to gush). As we approached the geysers, we could see steam emerging from the ground (in the above photo, you can see a small artificial structure that seems to serve as a chimney for the steam). It was a cold and grey day, windy and blustery. The plain reeked of sulphur, and yet I was tempted to stand in the odorous steam, just to get warm.
The Great Geysir is much less active these days, but Strokkur gushes quite regularly, every five to fifteen minutes or so. We got to see it three times while we were there. The first sign of the impending gush is when the water begins to "dome" in the center, as in the above photo.
Here is the plume of hot, sulphuric water. It can shoot up to 15-30m into the air. The crowd cheered at the impressive column of water. One visitor stood downwind, getting a face full of sulphuric steam at about this point.
Just after the gusher, there is a tremendous pull of water back into the hole in the ground, almost as if it were flushed away. Then the water comes back up to become a still pond again, until the next geyser plume.
Here is a video of Strokkur erupting:
And a short animated film that explains how geysers work:
You can find out more about how geysers work here and here.
Next up: Gullfoss