The Abyss under Grind Peak - the deepest cave in Romania

The Grind Sinkhole (Avenul de sub Vârful Grind), also known as The Grind Cave Shaft (Avenul din Grind) or The Cave Shaft beneath Grind Cliffs (Avenul de sub Colții Grindului), is a speleological natural reserve and a protected area of national interest located in Argeș County, within the administrative territory of Dâmbovicioara Commune, Romania.

It is currently the deepest cave shaft in Romania, reaching a depth of 769 meters. The shaft was discovered in 1985 in an area that has one of the greatest elevation differences in the country and is still being explored today.

The entrance to the Grind Sinkhole is situated at an altitude of approximately 1,922 meters on the eastern slope of the Piatra Craiului Mountains. It is located on the steep mountainside below the main ridge, within one of the Grind Gullies (steep mountain ravines).

The protected area, which is part of the Piatra Craiului National Park, consists of a vertical cave shaft (a subterranean void or cave), a collapse-type karst formation made up of several vertical pits interrupted by galleries, displaying visible features of erosion and corrosion.

The shaft was first explored in 1936 by Alfred Prox, who hoped to reach a hypothetical underground network within the Piatra Craiului Massif. In 1967, Friedrich Thomas and Walter Gutt from Brașov descended again to the bottom of the shaft and discovered a further 15-meter continuation, which they were unable to explore due to a lack of equipment.

In the autumn of 1985, the entrance to the shaft was discovered by Ioan Dobrescu and Ioan Bostan together with a team from the “Piatra Craiului” Speleology Club in Câmpulung Muscel.

The cave shaft is a typical alpine vertical system with very few horizontal sections. It consists of a sequence of 22 consecutive pits along the main route, without major tributaries. The longest side passage is intercepted at a depth of 167 meters.

Apart from this, the most significant lateral or parallel pit systems are the Himalaya 2 sector and the passage beneath Walter Gutt Pit, which rejoins the main route at a depth of 567 meters.

Due to its considerable vertical development, air temperatures in the lower parts of the shaft remain generally low, ranging between −2°C and −6°C throughout the year, becoming even colder during the winter season.

The Grind Sinkhole was formed by infiltrating water, which gradually enlarged a network of fractures affecting the Bucegi conglomerates. It is one of the few large vertical cave systems developed in conglomerate rock, a geological formation that is generally less susceptible to karstification.

Exploration of this cave shaft provides an excellent opportunity to study an interesting geological profile, allowing researchers to observe both the tectonics and stratigraphy of this sector of the Piatra Craiului Mountains.

Sources: Speosilex.ro, Speologie.org, AvenulGrind.ro, Silex Brașov Speleology Club.