The road north from Amasya toward Taşova leaves the narrow, hot air of the Yeşilırmak valley behind and climbs in bends along the eastern spurs of Akdağ. As the elevation rises, oak and scrub give way to Scots pine and beech, and the air cools. At about 1,050 metres, set inside a steep valley as if wedged into it, Lake Boraboy appears. The lake lies within the boundaries of Boraboy village in the district of Taşova. It is 61 to 63 kilometres from the provincial centre and, depending on the source, between 15 and 25 kilometres from the town of Taşova; the difference comes from the junction at which the road is measured. Declared a nature park together with its surroundings in 2013, the area protects one of the relatively few landslide-dammed lakes in Turkey.

The lake's name appears in the sources as Boraboy, Borabay and Gölbeyli, and foreign sources also use the name Lake Kocabey. Locals and travel writers mostly say Borabay, while official records and the name of the nature park use the spelling Boraboy. A widespread account holds that the village name goes back to the Bora clan, one of the Turkic tribes that came from Central Asia. This account rests on local memory and travel literature, and no written document has been offered for it; it should be cited as a common local belief.

How the Lake Formed

Boraboy is often assumed to be a crater lake. Volcanism, however, played no part in its formation; the lake is the work of a landslide. Located in the inner part of the Central Black Sea section, northeast of Amasya, it is described in the geomorphological literature as an old landslide-dammed lake. In the Black Sea Region, climate and landforms regularly set the stage for landslides. The streams that run through deep valleys are blocked by sliding masses, and water collects behind them. Sera, Tortum, Gaga and Yedigöller are well-known examples of this type, and Boraboy belongs to the same class.

The rocks around the lake explain the cause. On the eastern extension of Akdağ, between the Yeşilırmak and the Tersakan Stream, the area around the lake at roughly 1,045 metres brings together Permian crystalline limestones, Jurassic tuffs and agglomerates, and Pliocene continental sediments. The Jurassic unit, which covers the widest area, consists of tuffs and agglomerates interbedded with clay and sandstone; the diabase, andesite and porphyrite fragments in the agglomerates are cemented by tuff. This loose structure, prone to weathering, creates a setting favourable to landslides under the Black Sea climate. The region also lies in a tectonically active belt close to the North Anatolian Fault. The contacts between the formations around the lake mostly follow fault lines, and the crystalline limestones northeast of the lake are also bounded by faults.

The factor that directly prepared the landslide was the fault line between the Jurassic formation and the Permian limestones. Water seeping deep along the weak zone and fracture line produced by this fault made mass movement easier on the tuffs and agglomerates. The erosion surface of the region extends between 1,300 and 1,400 metres and is cut by a deep valley carved by the Boraboy Stream, which is called Çatağın Deresi in the upper part of the lake. The slope of this valley reaches 80 percent, and many side streams join it. The landslide began on the northern slope of the valley, in the section between Kaleboynu Tepe and the locality of Ardıçboğazı. The sliding material blocked the valley, and the water collecting in the depression behind the blockage formed the lake.

The details of the landslide mass have been measured. The mass begins south of Yanıklık Tepe with a distinct crown and extends about a kilometre to the south; its width is 450 to 500 metres at the crown and about a kilometre at the toe. Below the steep crown, the mass passes into steps of varying slope containing hollows and flats. In the part on which the lake sits there is little deformation, and the movement gives the impression of a rotational slump; at the eastern end of the toe, sliding marks are clear and heaps of kneaded debris are found. This debris was later deeply incised by the Boraboy Stream and its tributaries.

The change the landslide left in the longitudinal profile of the valley becomes clear when it is compared with the neighbouring valleys. When the profiles of the valley that holds the lake are set beside those of the Musullu Stream, three and a half kilometres to the north, and the Bostan Stream, one and a half kilometres to the south, the slope before the landslide proves to have been between 12 and 16 percent. In the area where the lake formed, the slope has dropped below 1 percent; in the eastern part of the dam, because of the heap formed by the debris, the slope reaches 20 percent, and the thickness of the toe in this section approaches 200 metres. The lake itself is a long, narrow water surface that follows the direction of its valley.

Dimensions and Discrepancies in the Sources

The dimensions of the lake vary from source to source. The differences depend on the year and the water level at which the measurement was made, and on the institution that compiled the data. The most frequently cited value for the deepest point is 11 metres: the 1994 study by Doğu, Çiçek and Gürgen of Ankara University, the 2014 statement of a Ministry of Forestry and Water Affairs official, and a 2025 magazine article agree on it. The 25 metres given on some travel sites rests on a different measurement. For the length, values such as 500, 675 and 750 metres are given. The width is shown as between 40 and 110 metres, and some sources say 80, 175 and 200 metres.

The scatter in the surface area is more pronounced. The ministry official gave the lake area as about four hectares, the 2025 magazine article gives a value just over ten hectares (10.75), and encyclopedic records report about eleven hectares (0.11 square kilometres). The figure of about three square kilometres in the text of Doğu and colleagues, read together with the 2 to 2.5 square kilometres given for the alluvial fill area west of the lake, looks like either a description that also covers the flat land outside the lake or a printing error; this reading rests on the internal inconsistency of the sources. For the elevation, the values of 1,045, 1,050 and 1,051 metres are close to one another, whereas the 1,500 metres in one encyclopedia entry contradicts all the other measurements. The lake is small, a long and narrow valley lake, and its depth is around eleven metres.

The Dam, the Weir and the Filling of the Lake

Because the natural dam risked breaching during floods, and because the lake is used for agricultural irrigation, it was later reinforced with concrete. The concrete weir built on top of the dam is about five metres high. The surplus water of the lake leaves through a spillway at the southern end of the weir; when the level rises excessively with rain or sudden snowmelt, the gates of the weir are opened to release the surplus. Because of the weir, the lake surface widens in spring and covers low-lying ground. The lake is thus a natural dammed lake that has also become a body of water shaped by nature and human intervention together.

The lake is slowly being filled by the alluvial and colluvial material brought by the Çatağın Deresi and its side streams. The fill area at the western end of the lake, between two and two and a half square kilometres in size, continues to grow toward the lake. This alluvial flat, covered with poplar and willow trees, is occasionally submerged when the lake level rises. The lake is fed by water from the stream and also by springs on its bed. The southern shore is steep and rugged, and the northern shore is gentler.

The most recent assessment of the lake's future is the geomorphometric study published in 2024 in the Journal of the Institute of Social Sciences of Ahi Evran University. Onur Yayla and Yıldırım Atayeter used three indices that measure the stability of landslide dams: the Blockage Index, the Impoundment Index and the Dimensionless Blockage Index. All three indices show Boraboy to be a stably formed landslide-dammed lake. The Blockage Index was found to be 8.97, the Impoundment Index 0.00021 and the Dimensionless Blockage Index -4.12. According to the authors, the lake has existed for a long time and is expected to remain stable in the future as long as suitable work is carried out on its drainage system. The same study stresses that new observations and research are needed with regard to tectonic movements near the North Anatolian Fault zone and to geomorphological processes in the region.

Among Turkey's Landslide-Dammed Lakes

The number of landslide-dammed lakes in Turkey is limited, and Boraboy is counted in this short list. Tortum, Sera, Zinav, Yedigöller and Abant are lakes placed in the same group. Most of these are much larger and deeper; Tortum is cited as the largest landslide dam in Turkey. Boraboy is one of the small and quiet examples in the group. Artificial lakes such as the Yedikır Dam on the Tersakan Stream also join the lake inventory of Amasya. Boraboy is one of the rare bodies of water in the province that formed naturally and is protected together with its surrounding forest cover.

Protection as a Nature Park

The protection of the area around the lake is not a new matter. The Ankara Regional Board for the Protection of Cultural and Natural Heritage, attached to the Ministry of Culture and Tourism, declared the area around the lake a first-degree natural site in 1993. Nature park status was granted much later, on 3 September 2013. The public announcement was made in February 2014, which is why some sources write that the park was established in 2014. Emin Karaman, director of the 11th Regional Directorate of Nature Conservation and National Parks of the Ministry of Forestry and Water Affairs, stated in his announcement that the area was 259 hectares; in later records the area is given as 255.34 hectares.

The main conservation value of the area is the lake itself; the landscape in which the wetland and the forest ecosystem form a whole is regarded as the park's principal resource value. The area is also protected because it contains endemic and endangered plant species, natural forests and habitats suitable for wildlife. Most of the land is state forest, and a very small part is agricultural land. The highest point of the park is Kaleboynu Tepesi, at 1,383 metres. The average elevation is around 1,215 metres, and the level of the lake itself is about 1,050 metres.

The first simple facilities around the lake were built in the 1970s. The General Directorate of Forestry created a forest recreation area around the lake and set up accommodation units for overnight stays alongside day-use facilities. Today the park has picnic grounds, recreation areas, a camping area and a nature walk of about two kilometres. Inside the forest there are wooden country houses equipped with a kitchen and basic fittings, and a country restaurant also serves visitors. The ministry official stated that the surroundings of the lake are suitable for hiking, nature sports, wildlife photography and similar ecotourism activities. Cycling around the lake and birdwatching are possible, as are tent camping and caravan tourism.

Visitor numbers show the pressure under which conservation operates. According to the figure cited on Wikipedia, about seventy thousand people visited the area in 2017. Quiet on weekdays, when visitors mostly come from nearby districts and villages, the area becomes crowded on weekends and in summer with visitors from neighbouring provinces. As early as 1994, researchers from Ankara University wrote that around the lake, which mostly served day-use visitors, insufficient importance was given to cleanliness and that clear environmental pollution had arisen. The same study says that the area, which holds important tourism potential for the region, could be protected and opened to more people through facilities in keeping with the natural character of the region, but that this must be done together with measures preventing the destruction of the surroundings and the disturbance of the natural balance.

Vegetation

The northern and southern slopes of the lake differ markedly. On the northern slopes of the lake, which extends in an east-west direction, coniferous forests dominate, and most of them are Scots pine. The species list given by the ministry includes oriental beech, black pine, Scots pine, Turkey oak and an endemic oak. On the southern slopes there are broadleaf forests dominated by hornbeam and beech; according to the ministry statement, the forest vegetation on these slopes gives way here and there to mixed scrub communities. Around the lake, in addition to mixed forest of oak, beech and hornbeam and stands of Scots pine, some sources also mention cedar trees.

The effect of logging and overgrazing has produced a distinct vegetation cover on the higher ground. On the open summit ridges there is an extensive steppe ecosystem made up of cushion-form plants. This steppe has the character of lowland and high-mountain steppe and has come about through human influence. On the alluvial flat west of the lake, groves of poplar and willow are found.

The botanical importance of the area comes from its endemic species. According to recent assessments, there are 245 endemic taxa within the boundaries of Amasya Province. Of these, 29 endemic species are distributed around Akdağ and Lake Boraboy and its surroundings. For this reason Boraboy and its surroundings are described as the most important endemic plant area of Amasya. A detailed list of which endemic species grow there is not found in the sources examined; only the number and the general importance of the area are stated.

Wildlife

The mammals known to be present in the park include roe deer, hare, wolf, fox, wild boar, squirrel, hedgehog, weasel and badger. The area also hosts many resident and migratory birds; quail, chukar and grey partridge are among the known species. The lake and its surroundings are a stopover point for migratory birds. Freshwater fish such as wels catfish and carp live in the lake; Doğu and colleagues also draw attention to the fish in the lake and write that boat trips are made.

These lists are of the nature of a general inventory. No published detailed monitoring study on the numbers, population status or seasonal movements of the species was found in the sources examined. The lists should therefore be read less as an exact census than as a framework showing that the area is rich in wildlife.

The Lake through the Seasons

The lake looks different in each of the four seasons. In spring the level rises with snowmelt and rain, the lake surface widens because of the weir, and the meadows around it come into flower. Summer is the season when people living in the lowlands escape the heat and take refuge in the coolness of the forest, and the lake is busiest in these months. In autumn the beech and hornbeam leaves turn yellow and red and are reflected on the surface of the lake; some visitors say this is the finest season. In winter the lake freezes over and the surroundings are covered with snow. In January 2016 the freezing of the lake also made its way into the press as a news item.

The Karaömer mountain range in which the area lies extends from Ladik in the west between Lake Ladik in the north and Akdağ in the south; its eastern boundary is formed by the town of Boraboy. The road to the lake follows the Taşova-Samsun road, which branches left at the 44th kilometre of the Amasya-Taşova highway, and turns left again at the 14th kilometre to reach the lake. For visitors without a vehicle, municipal buses are said to run from Taşova.

Boraboy Village and the Highland Pastures

Boraboy, from which the lake takes its name, is one of the villages in the high parts of Taşova, and the life of the local people is still bound up with livestock, highland pastures and small-scale farming. The Boraboy highlands consist of the Aşağıyayla, Yukarıyayla, Keçiyatağı, Çukuralan and Kozlu pastures. In spring and summer, products such as eggs, milk, butter and cheese are obtained in these pastures and sold to visitors. The local people make jams from fruits such as apple, rosehip, plum and quince by natural methods.

The local cuisine includes Boraboy meatballs, grilled dishes, stuffed pilaf, buffalo yoghurt, soups and şirvanlı helva. Festivals held in summer are also part of the social life of the region. The traditional way of life in the area rests on tolerance, solidarity and respect, and this is reflected to visitors as hospitality.

Chronology

Date uncertain: A landslide breaking away from the slope between Kaleboynu Tepe and Ardıçboğazı blocks the valley of the Çatağın Deresi, and the lake forms. The date of the landslide is not given in the sources examined.

1970s: The first simple facilities are built around the lake.

1993: The area around the lake is declared a first-degree natural site.

1994: The article "Borabay Gölü (Amasya)" by Doğu, Çiçek and Gürgen is published, treating the geology of the lake and its environmental problems in detail.

3 September 2013: The area is declared Boraboy Lake Nature Park.

18 February 2014: The declaration of the nature park is announced to the press; the area is reported as 259 hectares.

2016: News is published that the lake has frozen over.

2017: About 70,000 people are reported to have visited the area.

2024: Yayla and Atayeter publish a geomorphometric study classifying the lake as a stably formed landslide-dammed lake.

Sources

Academic studies

Official sources

Other sources

Online sources