Route 1 or the Ring Road (Icelandic: Þjóðvegur 1 or Hringvegur pronounced [ˈr̥iŋkˌvɛːɣʏr̥] ^ⓘ) is a national road in Iceland that circles the entire country. As a major trunk route, it is considered to be the most important piece of transport infrastructure in Iceland as it connects the majority of towns together in the most densely populated areas of the country. Economically, it carries a large proportion of goods traffic as well as tourist traffic. The total length of the road is 1,322 kilometres (821 mi), making it the longest ring road in Europe.

The road was completed in 1974, coinciding with the 1,100th anniversary of the country's settlement when the longest bridge in Iceland, crossing the Skeiðará river in the southeast, was opened. Previously, vehicles intending to travel between southern settlements, e.g. Vík to Höfn, had to travel north of the country through Akureyri, making the opening a major transport improvement to the country.

Many popular tourist attractions in Iceland, such as the Seljalandsfoss and Skógafoss waterfalls, Dyrhólaey cliffs, Jökulsárlón glacier lagoon, as well as Mývatn lake, Dettifoss and Goðafoss waterfalls in the north are easily accessible from the Ring Road. The road passes through almost all areas of the country (everywhere apart from the Westfjords), making it a popular itinerary to take for tourists and vacationing locals alike in Iceland.

The Ring Road is paved for all of its length and is mostly two lanes wide: one lane going in each direction. The Icelandic Road Administration, Vegagerðin, oversees the maintenance and operation of the Ring Road. The road is generally of good quality, recent road improvement projects have improved safety considerably. However the road still has hazards, going over many higher-altitude mountain passes in all parts of the country, which can have steep gradients and sharp curves, as well as blind curves and summits and single-lane bridges, especially in the more rural east of the country. Driving in winter one must take special precautions and pre-check driving conditions with the Icelandic Road Administration to ensure the road is passable.

The speed limit is 90 kilometres per hour (56 mph) on open sections; 70 kilometres per hour (43 mph) in tunnels and 50 kilometres per hour (31 mph) through urban areas. A few speed cameras operate on sections just outside of Reykjavík and in all tunnels.

In recent years, due to increased traffic and demands for higher road safety, many large improvements have been made in both capacity and safety of the ring road. In the southwestern corner of the country, between Kjalarnes and Selfoss and through Reykjavík, the road is usually divided by a barrier and has three or four lanes of traffic, mostly being a 2+1 lane partly-controlled access highway. At current traffic levels, 2+1 lane roads provide similar safety and traffic requirements to a regular expressway, and can be upgraded to a 4 lane road when traffic necessitates it.

The 7.4 km (4.6 mi) long Vaðlaheiðargöng tunnel near Akureyri in the north of the country shortened the route by 16 km (9.9 mi) and improved winter safety, bypassing a mountain road.

In more rural parts of the country, mostly in the glacial plains of the south and the Eastfjords, 31 single-lane bridges exist on the Ring Road. Dating back to the original construction of the road in the 1970s, they are sometimes constructed of wood or steel. Vehicles who approach the bridge first have the right of way. These are often narrow and long, making passing difficult, especially when there is high traffic.