Shelagh and I travelled from late August to early September. What an amazing place, but expensive!
We hired a car in Reykjavik drove the ring road round the island over 8 days: including places like Þingvellir Golden Circle, Geysir, Gullfoss, Selfoss, Skógar. Jökulsárlón, Höfn, Eskifjördur, Dettifoss, Myrvatn, Akureyri, Reykjavík. Then met up with friends and did two trips on the amazing 4WD buses to walk around Landmannerlaugar and later stayed in Þórsmörk.
We followed the Golden Circle route, along with busloads of thousands of tourists, (even on the 30th August) where we walked across the mid Atlantic Ridge, it is not a simple crack in the Earth but a wide flat area where you can see the Eurasian plate on one side and the North American one on the other. A humbling experience as the hills and fissures are all recent lava, just underneath our feet was a huge magma chamber filling in the crack as the two plates move inexorably apart up to 18mm a year (think 180cm a century). The magma can be very close. In the Krafla area drilling for geothermal energy found it only 2km down. Of course, the lava has regularly broken through, Iceland is the most volcanic area on Earth.
There is a deep connection between the origin of life on Earth and this great crack in the planet. In the depths of the ocean further, south, are hot springs, or black smokers, belching superheated sulphurous water into the cold Atlantic ocean. They are home to vast numbers of red and white tubeworms (like 2m long Riftia pachyptila) which feed from symbiotic sulphur bacteria in their bright red bodies, red from haemoglobin, as in our blood, which transports hydrogen sulphide (bad egg smelling, poisonous gas) and carbon dioxide to feed the bacteria which make food for them. The chimney-like black smokers are also crawling with blind shrimps called Rimicaris exoculata, which means the eyeless Rimicaris. They do actually have eyes, but not like those on most shrimps, looking like a pink patch on their backs, it can detect heat and help them not fall into the 400ºC black smoke. They can see in, total darkness! They also feed on sulphur bacteria.
But it is not here that life may have originated, but a few kilometres off to the side, in cooler hydrothermal vents called white smokers. Many scientists believe that it could have been in these vents that the first microbe cells on Earth arose, deep under the ocean surface. Life had an extreme origin.
Then onwards to the extraordinary geysers of Geysir. We wait by a deep blue hole, Strokkur, surrounded by red ochre, yellow and brown, muds and rocks, populated by thermophile bacteria and archaea. Then it begins to swell up into a huge blue bubble, then roar upwards into a massive water fountain, up to 30m high, of boiling and steaming spray. This water may have been below ground for thousands of years, passing through deep caverns and tubes, heated up to 200ºC but not boiling because of the high pressure. The water under the Great Geysir, Haukadalur, which only erupts a few times a year these days, is about 120ºC, like a great pressure cooker. This geyser used to reach 100m high in the past but has trouble with 10m now, maybe it is harder getting it up in old age? Geysers need an earthquake every few years, to clear the pipes, so it may yet regain its past glory. Even though some microbes can live at extremely high temperatures there are probably few under the rocks here but on the surface they thrive. Many are endemic, only found here, and cannot survive lower temperatures. Nearly 2,000 different species have been found in the hot surface waters. Far more species than plants or animals in Iceland, but far fewer than in nearby fertile soils where tens of thousands of species are found, possibly millions. Microbe biodiversity is immense.
You have to have a cup of the unforgettably Icelandic lamb soup, from the visitor centre here, and just about everywhere in Iceland, including the petrol stations. Warming and just delicious.