This isn't another dormant volcano, but that's in the ballpark.
Skútustaðagígar is a group of pseudo-craters that surround a pond. It seems that, once upon a time, hot lava passed over a small pond of water. Pressure built up, and explosions took place. The result was a crater.
Visitors can climb up to the edge of some of the craters, and a trail goes through the area. It takes about 45 minutes for a leisurely stroll through the area. This is down the road a bit from Godafoss.
