The Red Lake is one of the most beautiful lakes to be found in Seklerland. Regarding its formation several legends were told by father to son over the decades. Orbán Balázs, during his travels to every corner of the Sekler region gathered most of the legends of this Land, curiously doesn't mention a single tale about the Red Lake. Urmánczy Nándor was the first to write during his his itineraries about the legend, in which he memoralises a story told by an old Sekler man. According to the legend, an outlaw whose hiding spot was located in one of the caves of Mountain Suhardul Mare, had layed eyes on the beautiful Ferenc Anikó girl in Ditrău, kidnapped her from a fair and hid her in his hideaway. The girl cried and implored the help of good spirit of the cave to set her free and when the walls of the cave opened she managed to escape. When the outlaw came around, he banged the cliff with his bludgeon so powerfully in his fury that the mountain collapsed and closed the valley burying the outlaw under the falling rocks. As time went by other versions of the legend appeared. The popular belief connects the "killing" and the "red " adjectives with the legend, whereas the collapsing mountain buried under itself a grazing herd together with the overlooking shepherd, the blood oozed up and painted the water of the lake water red for quite a while.
Despite the fact that the Red Lake is a relatively young formation, the date and conditions of its formation are a subjecte for debate. At the time of its formation there weren't any commercial routes in the surroundings, it was an economically idle and difficult to access. Herbich F., the famous geologist of Seklerland, considers the year of 1838 as the formation date of the Red Lake. He argues in the favour of the year 1838, connecting the formation of the lake to the earthquake from January 1838, which repeated in February and could have set off a landslide. An other date would be 1837, when it poured heavy with rain in most of the year. About this period Ditrói Puskás F. wrote in his work entitled "History of Borsec". "...during this event the two Bicaz mountains collapsed, weakened by a huge mass of water, thus the path of the creek got blocked resulting in the Red Lake..."
The formation and the slip of the mass of debris to the foot of the „Ucigaşul” Mountain can be divided into three phases. In the first phase the basic debris has been conglomerated, which happened in the last stage of the periglacial period. In the second phase the slow weathering of the lower debris took place, finally the soaking of the debris, which set up the slide of the clayish stratum and led to the closing of the valley. We can see even today that headland, which closed the valley in its full width and now leans against the southeastern side of the Suhardul Mare.
The lake is bordered in the north by the Suhardul Mare and Suhardul Mic, in the southwest by the Calului Mountain, in the northwest by the Licoş and the Mic Mountains, in the northeast by the Csiki-Bükk, in the east by the Ucigaşul Mountain. The Red Lake’s water supply is provided by four constant and twelve periodical brooks, among which the most important are the Oii(Hăghimaş), Roşu, Licoş and Suhard.
Regarding the etimology of Red Lake, the original Hungarian name of the lake was also Red Lake, and those who wrote about the region used this name until 1864. In his presentation upon the assembly of the Transylvanian Museum Society, Orbán Balázs renames the lake as Killer Lake and suggests this name for wider use. It got its present Hungarian name probably from the Ucigaşul Mountain (means the Killer Mountain), which is much more older naming than the formation of the lake, as the documents mentioned it even in 1773 as the Lazar Counts' property; it was called "the mountain named Killer".
Source: Pál T. - Rab J. - Wild F. - Csíki K.