24 Hour Layover in Iceland (December)

Have a day in Iceland? I had a 24 hour stopover in Reykjavik with my parents after checking out the Christmas Markets in Germany/Czech R. and Austria. We rented a car which was pretty cheap, drove it from the airport to our hotel in the city, then set out at 8am to see Gullfoss Falls and Geysir, both a very short distance from eachother. Both destinations were incredible and the drive out was very scenic, feeling like we were driving in the Arctic. The sun didn't rise until around 11:45, so it was extremely dark when we left and the whole drive was like a slow motion sunrise. Since it was December, it was very cold everywhere, although there was no snow near the coast, almost the entirety of the road had varying layers of snow on it. We didn't stop anywhere for food, we ate in the car, stopping only to say high to the horses, a couple scenic photo ops, two bathroom breaks, gassed up the car before return (very expensive) then made it bake to the airport well before our flight. It would have been nice to spend more time in country, but for a short stopover, this itinerary, combined with checking out the city the night before, makes for a packed 24 hours. Video is done with a handycam and made more for family memories but should give you an idea of time and what you'll see.