Silfra and Þingvellir: Geology You Can Swim Through

Þingvellir sits about 50km northeast of Reykjavik, where the North American and Eurasian tectonic plates pull apart at roughly 2cm per year. The rift that separates them is a geological feature you can walk along, kayak, snorkel, or dive through depending on your preference. The water that fills Silfra fissure filters through lava rock for 40-100 years before it reaches the lake, which is why visibility here regularly exceeds 100 metres. It is some of the clearest fresh water on earth.

Snorkelling Silfra

The water is 2-4°C year-round. This is not metaphorically cold; it is genuinely cold in a way that takes your breath away the moment you slip in. Dry suits are mandatory on all guided tours, and there is no exception. The dry suit keeps most of your body temperature stable; your face, which remains exposed, goes numb within a few minutes and you stop caring.

The fissure runs for several hundred metres. The deeper channel, called Silfra Hall, has walls of volcanic rock with troll-hair algae (long strands of green algae that look exactly like the name suggests) waving in the current. Silfra Cathedral is the widest section. You can reach out and touch both the North American and Eurasian plates at once, which sounds gimmicky but you will absolutely do it.

Most guided tours run 2-3 hours and include equipment. Prices start around ISK 25,000-30,000 (roughly €170-200). DIVE.IS and Arctic Adventures are the established operators with good safety records.

Þingvellir National Park

The Althing, Iceland’s parliament, met here annually from 930 AD until 1798. It was not a parliament in the modern sense; it was a gathering of chieftains who settled disputes, announced laws from the Law Rock (Logberg), and occasionally executed people in the drowning pool. The site is preserved and marked, though there’s not much to see physically beyond the rift landscape itself and some informational boards.

Walk the main rift from the Hakid car park south to the church and farmhouse (Þingvellir Church, from the 11th century, rebuilt several times). The walk takes about 45 minutes at a gentle pace. The Oxara river runs through the rift and there are basic wooden bridges at intervals.

The national park visitor centre near the main parking area is good and free. The geology section explains the plate tectonics clearly enough that anyone can follow it.

Practical Notes

Þingvellir is part of the Golden Circle route (Þingvellir, Geysir, Gullfoss), which nearly every Iceland visitor does in a day. The downside is that this creates traffic at peak hours. Arrive before 09:00 or after 16:00 if you’re driving from Reykjavik; the roads and parking areas get genuinely congested in summer.

Entry to the national park itself is free. Parking costs ISK 750.

Accommodation near the park includes Hotel Grimsborgir (expensive, around ISK 50,000/night) and a national park campsite (cheap, around ISK 1,500/person). Most people stay in Reykjavik and day-trip.

There are no restaurants inside the park. A café at the service centre near the main parking area serves soup and sandwiches. For a proper meal, the nearest town is Selfoss (40km south) or you return to Reykjavik.