Mari is the most important deity in the Basque Mythology as she leads or guides the rest of the deities. This female personification of the earth is a vestige of the earth-based myths worshipped by the matriarchal communities before the arrival of the celestial gods/ goddesses. She is the queen of Nature and of all its elements. It is clear that Mari was already worshipped as a goddess by the ancient Basque before the arrival of Christianity. Considering her features, it appears that she could be linked to some other goddesses of the Old European Mythology.

She had many different names but, it seems that mari was the oldest. It does not seem to be related to the christian name Maria; on the contrary, it appears to be linked to some old names of the Basque Mythology, names such as Mairi, Maide, and Maindi.

Mari is the goddess of Justice; the defender of honesty. She reacts firmly against injustice. This goddess disapproves of lie, of stealing, of breaking one’s word, of being disrespectful to others and of arrogance; on the contrary, she rewards helping others. She helps and gives presents to those who believe in her; on the contrary, she punishes those who does not. She takes from the thieves what they store. And she deprives of his goods to those who are arrogant.

She symbolized Nature and, through her mighty power, she keeps the balance of the natural forces. She is the Queen of Nature; so, it rains when Mari approaches. In many places, she was begged to prevent hails the priest of the village would say mass at the entrance of her cave, as, even after being Christianized, Basques continued believing in Mari.

Many times, she has the appearance of an elegant woman. In Durango, she appeared with a golden palace in her hands; in Amezketa, she was seen crossing the sky in a cart pulled by four horses; in Oñati, riding a ram. In some legend, she has the appearance of an animal, of a sickle in fire, of a blow of wind, of clouds and of a rainbow. At the entrance of her cave, she appears next to a ram, her favourite animal. At the entrance of her cave in Mount Anboto, she was also seen while she wound golden thread into a ball in the horn of a ram.

Mari, being an earth-based mythological character, live underground and she comes outside through the caves and chasms. She punishes anyone entering her refuge; but, if someone approaches her with her permission, she/he must address her as hi (second person singular, used on familiar terms in the Basque language); she/he must not sit down in her presence and she/he must never turn her/his back on Mari.

In Oñati, the God Maju is told to be Mari’s husband; however, according to the legends in Goierri, it is Sugaar. It seems that her sons are the Gods Mikelats and Atarrabi.

According to a legend in Amezketa, Mari disappeared for seven years from her cave in Mount Txindoki. But, suddenly, the villagers realized that she was back when they saw a horse flying in the sky, followed by a heavy shower. She lived in a caved Marizulo, which was full of gold. It appears that everything inside was made of gold, even the furniture. On one occasion, after several weeks of rain, when it stopped and cleared up the Txindoki was left with a cloud covering its summit. Then. the villagers realized that Mari had lighted her oven.

One morning, a young girl from Amezketa called Kattalin went to the mountains with her flock and, after spending the whole day in the pastureland, gathered the sheep. But, when she counted them, she realized that there was one missing. She was afraid of what the owner of the sheep would do to her and, therefore, she climbed the mountain to find the missing sheep. Kattalin had been advised not to approach the cave when Mari was in Mountain Txindoki but she needed to find the missing sheep. When she reached the cave, she saw the sheep at the entrance and, next to it, the most beautiful and elegant lady she had ever seen. It was Mari. Mari asked the girl who she was and who her parents were. The girl answered that her name was Kattalin, she had no family at all and the sheep belonged to a nobleman from her village. Then, Mari suggested to Kattalin that, if she spent seven years living with her and helping her, after those years, the goddess would make her rich.

Kattalin accepted the proposal and remained in Marizulo Cave helping the lady; she learned a lot in those seven years: to spin a thread, to make bread, to know the magical features of the plants, to understand the language of the animals and so on. The years went by really quickly and, at the end of the seventh, mari said:

- Kattalin, you have kept to your word and you have helped me a lot. Now, I must leave and, as I told you that I would make you rich, here you are!

Them, Mari gave her a big coalstone. The young girl got surprised but she did not dare to say a word. A soon as she came out of the cave, the coalstone became a shining goldstone. The girl, full of joy, went down to the village, where she bought a house and a flock of sheep; and she lived the rest of her life happy and without taking orders from anyone else.