Driving in the dark near Reykjavik on Highway 1

We want to rent a car but will end up driving in the dark on Highway 1 near Reykjavik. How is the driving in the dark? Are the roads well marked? Visibility?

How far from Reykjavik? You can get some idea of the road by looking at Google street view. For example, this is about 10km from the city center: https://goo.gl/maps/tdbp78X4BZS2 If you are traveling further from the capital, the road has more curves and hills, so long-range visibility starts to drop. You'll also encounter several single lane bridges, so read up on the road etiquette for handling them. Much of the road is not externally lit, and there is little no shoulder area, but the lane markings and signage are generally quite clear.

There are good reflectors at the side of the road, pretty much on every road.

Check out the beginning of this video, or the part that starts around 1:10 in:

What time of year are you there and what time of day?

There are no street lights and very few guardrails, so it's important that the driver is very alert and not siteseeing as there are severe dropoffs from the road along most of it's length, to allow snow to blow off of the surface

We were there for four days in June/18 driving Route 1 near Reykjavik. The road is asphalt in excellent condition, one lane each way, paint lines well-marked, narrow lanes and also narrow shoulders, with a sharp drop off of several feet beyond the shoulders. Drivers are polite and follow the rules. Visibility depends on the weather. If there is rain driven by wind, it will be difficult.

It basically never got dark when I was there. I suppose it could be difficult if you are not used to rural driving but just reduce your speed and you should be fine. Highbeams are your friend. Generally I find rural driving easier in some ways at night as you will see the other cars coming very clearly with headlights so you can hug the middle almost everywhere expect a completely blind curve.

Good point. Depending on when you go, the total amount of real darkness may be very low. There will be a long dusk/dawn, where headlights should be used, but that's not the same as dark.

For the OP, I'm assuming you'll be there with a cruise, so sometime May-September? Anything outside of those months is winter, and the dark is not the issue, but the weather can be.