Volcanoes, fumaroles, waterfalls, lakes, colorful mountains, geothermal springs, glaciers, deserts, fjords, puffins, seals, midnight sun ... everything is found together in Iceland.
The most surprising for me, will remain the variations of landscapes over short distances.
In Iceland, clouds are part of the landscape. Some places will appear mysterious under a soft light in cloudy (or even rainy) weather but surprisingly more ordinary under the sun.
It is good to know that summer is very short there. There may still have heavy snowfall until mid-June and the rain may become crippling from August. Paradoxically in summer, the North enjoys a warmer and drier climate than the South, which is much rainy.