Hveragerði has a small geothermal park in the town centre where visitors can see hot springs, mud pools, and steam vents at close range without any hiking. The park is low-key — more of a maintained geothermal area than a formal attraction — but it does what it sets out to do: gets you close to the visible evidence of volcanic activity in a safe, accessible way.
The ground temperature in parts of the park is high enough that the town tradition of burying pots of bread dough to cook underground actually works. A few local bakeries and restaurants demonstrate this, and the resulting rúgbrauð (hot-spring bread) has a distinctive dense texture and slight sulphurous edge. It is served with Icelandic butter and smoked lamb, which is about as local a food experience as Hveragerði offers.