Time to pick up a rental car so we can explore wider than Reykjavik! We got a Hyundai Tucson PlugIn which was just big enough to hold us and our copious luggage. Imagine our surprise when (later) we went to fill it up, opened the hatch and found electrical connections! Luckily there was another hatch on the other side with took Benzin! We really don't know how a plugin works, but we did note that during the entire week we had the car, the electric charge gauge never moved from 25% no matter how far we drove. Obviously the petrol engine does not charge the battery. Maybe there are settings on the car we didn't know about. [Looking it up later, this car must have been a PHEV, a plug-in hybrid electric vehicle.]
Our rental Hyundai Tucson Plugin clinging to the last parking spot at Kerið on the Golden Circle route. 
We set out to follow Iceland's famous Golden Circle anticlockwise, with some trepidation because we feared heavy traffic, but except as noted below, we never encountered it. The Golden Circle is iconic but not signposted: we just had to be guided by our map and an old GPS navigator loaded with Europe maps that we brought from Australia. And it's not a circle either, but a lumpy triangle with whiskers. The distance around is about 250km if you don't take any side trips. Many visitors make a day trip of the whole loop (after all, it's daylight all night), but we spent 4 days on the Golden Circle so as to better appreciate it.
It was way overdue time that we improved our understanding of the 32 character Icelandic alphabet, in the (vain) hope we might improve our pronuciation of placenames that we visited and tried to say. One letter we really got into trouble with was eth ( ð ) which, in its lower case form, looks like an 'o' with an accent, but is more properly transliterated as 'd'. Another was thorn ( þ ) which sounds like 'th' and is often thus represented. There's also letters like æ and ö which contribute to Icelandic's rather big alphabet. According to Wikipedia, eth is also used in Faroese, whereas thorn is unique to Icelandic, although it was used in Old English. We just have no hope of handling this alphabet or Icelandic pronunciation. See how we go in the rest of this blog!
Highway 1 out of Reykjavik took us through a geothermal park called Hveragerði (pronounce that second last letter as a 'd'), and then to the town of Sellfoss. Expert Icelanders that we are thought that any suffix 'foss' would mean a waterfall, but when we asked about it at the tourist information centre, they laughed and repeated what we had heard before about Iceland not being icy and Greenland not being green! Foss does not guarantee a waterfall, although the river through town, the Ölfusá did sport some nice cascades. Sellfoss is where we encountered the heaviest traffic we had seen so far, with a long queue of cars coming from Reykjavik or Gullfoss (where there is a genuine waterfall) all being held up at an unavoidable roundabout in town. (Australians familiar with Byron Bay will recognise this layout.)
1891 saw the first bridge over Ölfusá, but this suspension bridge at Selfoss dates from 1945. 
Disappointed with no waterfall in Sellfoss, but now equipped with a half decent Golden Circle area map, we headed away from the Circle and south to the Atlantic coast for a quick look at part of the South Coast Lighthouse Trail. The biggest of the lighthouses is Knarraros (26m, 1939) near the town of Stokkseyri so that's the one we visited. We were almost on our own out here. The town looked like a mid-week beach village, i.e. deserted, there was the odd horse in a field, and the only two people we saw were riding bicycles along a coastal trail. The lighthouse itself has a sqaure cross-section so it looks more like a tall, skinny concrete building downtown than a lighthouse.
Then back through Sellfoss (the traffic coming from Reykjavik was now even worse) and north-east on Highway 35. The highway is a good, sealed two lane road which would not like too much traffic, but we found it realtively quiet. We arrived at Kerið, a 55m deep volcanic explosion crater, half-full of water, about 3000 years old. This was the only 'attraction' on the Golden Circle that we had to pay to visit. It's apparently on private land. The entrance fee did not discourage visitors because the carpark was full and the path around the crater rim and down to the lake was quite busy. Kerið is just one of a group of craters called Tjarnarholar.
Next highlight was Geysir (Icelandic verb: to gush), the gusher after which all the world's geysers ( periodically spouting hot springs ) are named, being the first known to Europeans. The actual Geysir geyser, active for 10,000 years, since 1916 no longer spouts. Earthquake activity changes geyser behaviour. Only 50m away, the Strokkur geyser goes off every 10 minutes or so (not as regular or predictable os Old Faithful in Yellowstone), and it's certainly pretty spectacular with spouts up to 30m high. In the immediate vicinity there are around thirty much smaller geysers and hot pools bubbling away. Gift shops and accommodation are over the road at Geysir, and barely enough parking for the crowds.
Geysir, the geyser after which all the world's geysers are named, has hardly ever erupted since 1916. 
Stokkur, which erupts every several minutes, but not to a regular timetable, attracts a good crowd. 
Strokkur gives almost no warning of an eruption. Then, in a fraction of a second, a huge bubble forms which bursts into a tall spout. 
We enjoyed dinner one evening at the Geysir Restaurant which is attached to the modern Geysir Hotel. 
Still on Highway 35, only 10km from Geysir is Gullfoss ('golden falls'), a magnificent three-step cascading waterfall on the Hvítá river which runs into the Ölfusá near Sellfoss. The total fall is about 60m. The falls are now in public ownership, although they were once considered for a hydro-electric power station. These awesome falls were very popular with visitors - the quietest we saw them was during an early morning walk.
The bottom falls at Gullfoss where the river makes an abrupt left hand turn and heads towards our hotel. 
Highway 35 sort of bisects the nation, running from Highway 1 on the south side of the island, to Highway 1 on the north. Past Gullfoss, 35 turns to dirt and a sign advising that the next petrol is 205km away reminds careless navigators that they have well and truly left the Golden Circle! We retreated from 35 back to follow the rest of the Circle, with our next major stop being Þingvellir National Park, or Thingvellir if you don't have a fancy keyboard. We weren't sure what to expect here, and to tell the truth, we didn't expect to spend any time here. But we were at first stunned by the hundreds if not thousands of other people we found here, and it took us an hour to find a parking space. In the end, we spent several hours at this fascinating place.
Þingvellir's attraction is multi-faceted. Firstly, and most obviously, it's a place where Iceland's stark geological processes are there before your eyes. As we have said before, Iceland is neatly divided by the Mid-Atlantic Rift. In continental drift theory, the west of the country (where Reykjavik and the Westfjords are) is on the North American tectonic plate, and the east (where Vatnajökull glacier and the East Fjords are) is on the Eurasian plate. To quote a guide, 'Iceland is the only place in the world where this rift is above sea-level, and nowhere can you see the edges of both plates as clearly as in Þingvellir'. In our case, we drove down the steep walls of a valley on the edge of Eurasia, across the rift, then up the other side into North America.
In Þingvellir is Þingvallatn, Iceland's largest lake (84km2) fed mostly by underground channels from the Langjökull glacier. It takes 20-30 years for melt from the glacier to reach the lake. 
For 60 years from 874AD, the early Norse settlers in Iceland, fed up with fighting each other, chose Þingvellir as a suitable neutral territory to iron out their differences. In 930AD, over 30 chiefs from all over the island met for the first time to standardise law and create a crude version of what would now be considered a representative parliament, the first in the world and about 800 years before such concepts arrived in North America and Europe. The chiefs liked their work and started to meet each year. They called their gatherings Alþingi and the word Þingvellir means 'fields of parliament'. The Alþingi has operated continuously since, even throughout the Icelandic Civil War in the 13th Century. The only interruptions was between 1799 to 1844 due to Danish colonialism. When it returned, it was the same institution under the same name, but they moved the meeting place to Reykjavík, where it continues today. This makes Þingvellir the original site of the world’s longest running, still ongoing parliament. Unlike the Mid-Atlantic Rift, there is very little evidence of the Alþingi at Þingvellir. Temporary shelters were built for the meetings, and there are almost no remains, but thanks to that history, this site is of tremendous significance to Icelanders.
Remnants of temporary shelters from ancient Alþingi have been found in the flat valley between the two continental plates. 
As a base for our exploration of the Golden Circle, we stayed at the Gullfoss Hotel, a low slung 30 room establishment with a good restaurant located on a farm land about 3km down the valley from Gullfoss falls. It was a pleasant (although rough underfoot) walk along a bridle trail to the falls before breakfast one morning.
The Gullfoss Hotel was our home whilst exploring the Golden Circle. We were in the new wing to the left. 
Our room at the Gullfoss Hotel with a splendic picture of the Strokkur geyser in the first split second of an eruption.