Diamond geysers, belching mud pools and steaming lakes are thrilling sights on this New Scientist tour of Iceland

We are in the middle of a vast plain of jagged, gray-green lava rocks, atop miles of gashes in the Earth’s crust, where two continents – Europe and America – are slowly tearing apart.

And I’m standing right next to the oldest parliament in the world, dating from 930, listening to a story about witches’ cooking.

If that sounds a bit overdramatic, that’s because it is. This is Thingvellir, a huge natural amphitheater, full of grumpy volcanoes, belches and steaming lakes (hence the witches), in the far south-west of Iceland, about an hour outside the capital Reykjavik.

I’m on a special one New Scientist tour of the geology, history and ecology of this unique island, and I’m already learning that everything in Iceland comes with a touch of flamboyant terror – and that includes the price of alcohol (best advice: buy your booze at the liquor store of government).

From Thingvellir we continue to Geysir. This is the original ‘geyser’, but today it is Geysir’s sister, Strokkur, that delights tourists. Every ten minutes it erupts into a source of hot steam and liquid.

It shouldn’t be as fun as it is. Sometimes Strokkur makes you wait a few extra minutes, which increases the tension. Then: whoomph! Occasionally, as if for variety, he has a noose and sends out a few ten-foot runs in a few seconds, drenching the unwary.

Every time Strokkur does his shtick, the audience bursts into laughter – and then we all march to the modern, airy café for some much-needed refreshment. Try the lamb soup with thyme, possibly with a nice chilled Einstok Arctic Pale Ale.

From here we drive to a pleasantly chic four-star hotel in the small village of Vik on the south coast. We get a lecture on magma and delicious cod, plus skyr cake with red berry sauce, and a precious chance to see the ethereal green curtains of the Northern Lights – best seen from the beautiful hilltop church.

Above it lies Thingvellir, a ‘vast natural amphitheater, full of grumpy volcanoes, belching mud pools and steaming lakes’ in the far southwest of Iceland

Make sure you bring warm toddy, warm hat and gloves, and a dedicated Northern Lights spotting phone app, such as My Aurora Forecast. Also bring plenty of patience.

The next day we aim inland aboard an Icelandic Superjeep, passing acid farmlands, steaming geothermal power plants and the strangely remarkable museum-like Lava Center, which features ‘earthquake corridors’ and mighty 3D models of ‘mantle plumes’.

We also take in the evocative, blood-soaked Icelandic history. The old church of Hofskirkja, for example, with its sod roof, spooky cemetery, pagan foundations and sacrificial stone altar.

Sean (not pictured) describes Vatnajokull Ice Cave, located in Europe’s largest glacier, as a ‘miracle’

Then we get beautifully lost in the central wilderness of steep cataracts and dwarf glaciers. As we soak in the grandeur, we drink the fragrant local schnapps, called Brennivin, to wash down bits of fermented shark meat known as hakarl. The schnapps is delicious…

After this, the days blur into a brilliant swirl of terrifying, gruesome wonders.

First comes Reynisfjara, a realm of towering dark sea stacks, elegant stretches of charcoal-black sand and hexagonal terraces of basalt cliffs. It’s as if Ibiza has been redesigned by the devil.

Above you see a harbor seal in the Jokulsarlon Glacier Lagoon, an environment ‘particularly striking’ at dusk

Sean explores Reynisfjara Beach (above), a realm of towering dark sea stacks, elegant stretches of charcoal-black sand and hexagonal terraces of basalt cliffs

Above is a bottle of Brennivin – Iceland’s signature drink, which helps wash down the delicacy of fermented shark meat

Not far away is the Jokulsarlon Glacier Lagoon, where seals swim among white, gray and turquoise icebergs. At dusk, Jokulsarlon is especially striking, as the slanting northern sunlight glows through the ice, transforming them into miniature, translucent, blue-lit Taj Mahals, floating dreamily towards the darkening sea.

Now comes the ultimate wonder of all: the Vatnajokull Ice Cave, located in the largest glacier in Europe.

We run through the barren plains to get there. Then we put on the obligatory helmet and headlamps – ice caves are dangerous – and start the walk across the Mordor black sands. An hour later we are confronted with a memorable cut in the gray-white glacier. This is the gaping entrance to the ice cave. Inside we walk along dripping wet paths, before the guide tells us to turn off the headlights and let the darkness ensue. Why? Because it is not real darkness. As our eyes adjust, we realize we are surrounded by thousands of years of frozen time.

Above us, beside us, and around us are ice walls, floors, and ceilings, all shot through with ancient blue daylight, even as the cave shifts and melts into a million tinkling waterfalls.

It’s like a surreal and crystalline hallucination. It’s scary, strange, moving and wonderful.

It’s the glorious, icy heart of the land of ice and fire, and it’s totally worth it, despite the terrifying price of beer.