Red Lake (also known as Killer Lake) is a natural dam lake formed following the collapse of a slope due to the earthquake of January 23, 1838, 6.9 magnitude intensity. The lake was formed at an altitude of 983 m, in a depression with a predominant subalpine climate.

But here is the beautiful Legend of Killer Lake

Once upon a time there lived in the vicinity of Gyergyó a beautiful girl named Eszter Fazekas. Her hair was pitch-black, her eyes grey-green, her figure like a proud maiden swaying in the wind. On a sunny July morning, Eszter went to the fair in Szentmiklós. There he met a boy from Dali who squeezed the puss out of a bear with both arms, and who played the most heart-warming flute in the whole neighborhood, but he could also do housework and carve a cart. As their eyes flashed - and because love comes suddenly and strikes the heart like lightning - they fell in love.

The boy bought Eszter a sky-blue silk scarf for the mirror cake and asked her to be his matka. The wedding could not take place because the young man was taken as a soldier. The girl faithfully waited for her lover.

In the evenings, when the sun went down behind the mountains, he went out with his clay jar to the fountain under the pines and there he yearned for his beloved for hours. Even the nearby mountains had their hearts softened by his sighs and his painfully beautiful singing.

However, it happened one Sunday afternoon that a rogue leader saw Eszter while she was there. He took the beautiful girl in his saddle and galloped with her like a gale to Kis-Cohárd, between the thousand-faced rocks where he had his ranch.
He promised Eszter his gold and silver, he wanted to build a diamond palace, just to make her fall in love with him. The young girl did not return the rogue's love. He was waiting for his old mother when the sun rose, and also when the world closed its eyes.

Seeing this, the rascal got angry and wanted to force Eszter to be his wife. Eszter cried out to the silent witnesses and the mountains for help. The rocks understood her scream and on this July night they answered with thunder that shook the sky and the earth. The rain poured down, the zigzagging lightning lit up the pitch black night.

At dawn, huge pieces of rock fell into the depths with a huge crash, and the terrible earthquake buried everything under it, the girl, the rascal, and even the gentle shepherd who was grazing on the opposite mountainside.

At dawn on the last Sunday of July, the first golden rays of the sun lit up the rocky countryside. The valley, where yesterday the Vereskő stream flowed with its crystal clear water, was completely blocked by the collapsed mountainside. When the murky water from the flooded streams reached the top of the rock dam, it suffocated grasses, bushes and killed trees.

In the place of the narrow valley, a lake was created, from whose water the remains of the pine forest still stand. The shepherds of the area named this lake Gyilkos lake. This is how the death of the mountain became the water of life.

If you look into the water of the lake in the sun, Eszter's gray-green eyes look back gently.