Ljótipollur is a maar-type explosion crater, formed during a violent phreatomagmatic eruption when magma interacted with groundwater. The crater is generally dated to the late 15th century, most commonly associated with the 1477 Veiðivötn eruption, the same eruptive episode responsible for several prominent volcanic features across the central highlands and Fjallabak area.

Unlike shield volcanoes or fissure-fed lava fields, maar craters are defined by excavation rather than construction. Ljótipollur was created when explosive forces blasted existing material outward, leaving behind a steep-sided depression that later filled with water. This origin explains the crater’s sharply defined rim and the contrasting layers of material visible on its slopes.

The surrounding colours—reds, browns, blacks, and muted greens—are the result of oxidised volcanic tephra mixed with basaltic fragments. Iron-rich material, exposed to air and weather over centuries, produces the characteristic red tones that make Ljótipollur immediately recognisable, even from a distance.

The lake, sediment, and visual character

The lake within Ljótipollur occupies much of the crater floor and is notably deeper than many nearby highland lakes. While precise depth measurements vary by source and season, it is commonly cited as being over 40 metres deep, reinforcing the impression of a substantial water body rather than a shallow pond.

Water colour in Ljótipollur shifts between dark blue, grey-blue, and greenish tones depending on light conditions, cloud cover, and wind. Unlike the milky turquoise seen in glacially fed waters, Ljótipollur’s colour is clearer and darker, reflecting both its depth and the absence of significant suspended glacial sediment. The surface often appears calm, protected from wind by the crater walls, which enhances reflections and tonal depth.

Vegetation is sparse on the inner slopes, limited to mosses and hardy plants capable of surviving in loose volcanic material. The relative lack of plant cover keeps the geological structure exposed and readable, allowing visitors to observe layering, erosion patterns, and gravity-driven movement of material downslope.

Access, perspective, and place within Fjallabak

Ljótipollur is reached via a short side road from F208, typically navigable by high-clearance vehicles during the summer highland season. From the parking area, a brief walk leads to the crater rim, where the full form of the lake and surrounding slopes becomes visible. There is no developed infrastructure at the site—no platforms or barriers—so visitors experience the crater directly, with minimal mediation.

From an observational standpoint, Ljótipollur works exceptionally well because its entire structure can be understood from a single elevated viewpoint. The crater rim provides a complete overview: the symmetry of the depression, the distribution of colour, and the relationship between water and rock are immediately legible. This clarity is one reason Ljótipollur has become a key visual reference point in discussions of Icelandic explosive volcanism.

Within the broader Fjallabak landscape, Ljótipollur contrasts strongly with nearby features such as Hnausapollur and Frostastaðavatn. Where Hnausapollur emphasises colour through suspended sediment and Frostastaðavatn through reflection, Ljótipollur derives its impact from depth and enclosure. It feels inward-looking—a contained system rather than an open basin.

Despite increasing visibility in photographs and travel media, Ljótipollur retains a sense of restraint. It does not invite movement through the landscape in the way hiking areas do; instead, it encourages stillness and observation. This makes it an effective counterpoint to the more active geothermal and trail-based experiences nearby.

• Misleading name: Ljótipollur translates to “Ugly Puddle,” a name widely considered ironic given the crater’s visual appeal.
• Maar crater: Formed by an explosive interaction between magma and groundwater.
• Significant depth: Often cited as being over 40 m deep, unusually deep for a highland crater lake.
• Historic eruption: Associated with the 1477 Veiðivötn eruption, one of Iceland’s largest historical volcanic events.