Kerið

Kerið is a striking volcanic crater lake in southern Iceland's Grímsnes area, renowned for its vivid aquamarine waters contrasting dramatically with steep red and rust-coloured slopes. Approximately 6,500 years old, making it relatively young by geological standards, this elliptical crater measures 270 metres long, 170 metres wide, and 55 metres deep. ^[1] Unlike most volcanic craters formed by explosive eruptions, Kerið was created when a cone volcano's magma chamber emptied and the ground above collapsed inward. Often included as an addition to Iceland's famous Golden Circle tourist route, the crater has earned the nickname 'Blue Eye of Iceland' for its remarkable colouration and photogenic qualities.

The crater lake and surrounding slopes support a limited but distinctive ecosystem adapted to the volcanic environment. Various species of diving ducks and other waterfowl occasionally visit the aquamarine lake, while the surrounding grasslands attract typical Icelandic meadow birds. Ravens and other corvids frequent the area, taking advantage of the open landscape for foraging. The mineral-rich waters of the crater lake support some algae growth but limited aquatic life due to the relatively sterile volcanic conditions. Insects including various fly species thrive during summer months, attracting insectivorous birds.

Vegetation on Kerið's slopes varies dramatically based on age and stability of the volcanic material. The gentler western slope supports a thick carpet of deep green moss that has established itself over millennia, creating a striking contrast with the barren red slopes. This sloped section can be carefully descended, allowing close observation of the moss communities. The steep crater walls remain largely unvegetated, with fresh-looking red volcanic rock exposed where erosion prevents plant establishment. Arctic grasses and hardy flowering plants colonise stable areas around the crater rim, while lichens slowly break down rock surfaces in early successional stages.

Kerið belongs to a group of volcanic craters in the Western Volcanic Zone, formed during eruptions along the same fissure system. Unlike craters created by purely explosive volcanism, Kerið formed through subsidence when the underlying magma chamber drained, causing the surface to collapse into the void below — a formation mechanism that explains the crater's relatively gentle slopes compared to explosively formed craters. ^[1] At approximately 6,500 years old, Kerið is relatively young, which explains why its slopes retain vivid red colouration from iron-rich volcanic rock that has not yet fully weathered to black. The lake fills the crater to a depth of 6–14 metres, its level fluctuating with groundwater rather than rainfall.

Kerið experiences the temperate oceanic climate of south-western Iceland, with cool summers, mild winters, and significant precipitation distributed throughout the year. Summer temperatures typically reach 10-15°C, while winter temperatures hover near freezing with occasional cold periods. The crater's orientation provides some shelter from prevailing winds, though exposed sections can be quite breezy. The aquamarine lake rarely freezes completely due to its depth and groundwater connection, though ice may form around the edges during cold snaps. The location away from urban areas makes Kerið an excellent spot for northern lights viewing during clear winter nights, with the aurora potentially reflecting in the crater lake's still waters.

The Grímsnes area where Kerið sits has been inhabited since Viking settlement of Iceland, with local farmers utilising the surrounding fertile lands for agriculture. The crater itself held significance in Norse and later Christian traditions, with its unusual appearance inspiring local legends and folklore. The name Kerið likely derives from the Old Norse/Icelandic word keri, meaning vessel or bowl, reflecting its distinctive shape. The site has served as a local landmark for centuries, with the vivid colours and unique formation attracting attention long before modern tourism development.

Kerið has been recognised as a protected natural feature and popular visitor destination for decades, with its inclusion in extended Golden Circle itineraries driving significant tourism. The site is privately owned and operated, with Arctic Adventures having acquired it and charging a modest entrance fee (700 ISK) to support maintenance and conservation. ^[1] A well-maintained pathway around the crater rim was established to provide safe access while protecting the fragile slopes from erosion. The gentler western slope has been accessible for descent to the lake edge, allowing visitors closer appreciation of the aquamarine waters.

A walking path circles the entire crater rim, offering continuously changing perspectives of the aquamarine lake and multi-coloured slopes. The complete circuit takes approximately 20–30 minutes at a leisurely pace and includes several viewpoint areas optimal for photography. The gently sloped western wall allows visitors to descend to the water's edge, experiencing the crater from lake level and appreciating the scale of the formation. The vivid colour contrasts between blue-green water, red crater walls, and green moss-covered slopes create exceptional photographic opportunities, particularly during golden hour lighting.

Kerið is located approximately 55 kilometres northeast of Reykjavík via Route 1 and Route 35, requiring about 45 minutes of driving. The site is often combined with Golden Circle tours as an additional stop beyond the classic Þingvellir, Geysir, and Gullfoss attractions. An entrance fee provides access to the crater and maintained pathways. ^[1] Parking accommodates numerous vehicles, and basic restroom facilities are available. No food service is available at the crater; the nearest restaurants and services are in nearby towns.

Conservation efforts at Kerið focus on protecting the fragile volcanic slopes and unique colouration that make the crater special. The established pathway system prevents visitors from trampling vegetation and causing erosion on the unstable crater walls. The entrance fee supports ongoing maintenance of facilities and trails while providing resources for protective measures. The moss-covered western slope is particularly vulnerable to foot traffic, requiring visitors to stay on designated routes. Climate change may affect groundwater levels that maintain the crater lake, potentially altering this iconic feature over time. Educational signage encourages visitors to appreciate the geological significance while minimising their impact on this young and fragile volcanic landscape.