In the Northern part of lake Onega is zaonezhskiy Peninsula. He enters the territory of Medvezhiegorsk region of Karelia. This unique historical and cultural complex rich in mineral springs. One of the most popular sources is - "Tsar's key", located towards the great Bay, 5 kilometres from the township of tavua and 70 metres from the highway. The first mention of the churchyard tolua is found in documents of the fourteenth century. It is one of the oldest Russian settlements on the shores of lake Onego. In the early 18th century about Tolvun churchyard was 33 settlements.

Village tolua surrounded on three sides by the waters of lake Onega. A special microclimate here, possibly due to the Deposit of shungite - the stone has unique healing properties. As has long been known and the healing properties of water sources in the area. The locals used them long before 1714, when they were discovered is known around the world Marcial ferruginous water.

This spring has a long history associated with the Romanov dynasty. It is named in memory of the mother of the first Russian Tsar Mikhail Fedorovich – the nun Marfa, which the locals called "the Queen". At the end of the XVI century on the throne of reign of Boris Godunov, and because he was not the heir to the throne by Royal blood, he sought to get rid of possible rivals for the Imperial family. The boyar Fyodor Romanov and his children were the most likely contenders for the throne, as it had by the brother of the spouse of Ivan the terrible – Anastasia. Feodor Nikitich was sent to Antony of siya monastery. His son Michael and sister were taken away in White lake. His wife, Ksenia Ivanovna, made her a monk with the name Martha and exiled from 1601 to g on tolvun churchyard.

The tower, which housed the unfortunate prisoner, was small and stood behind the peasant's house, near the Church. On Tolvun townland in 17th century there were three churches: Holy Trinity, St. George, St. Nicholas. In 1869 on the site of the wooden St. George Church was built of stone, still preserved. In place of Trinity Church in the early 20th century, built a chapel in memory of the 300th anniversary of the Romanov dynasty. In the ecclesiastical annals indicate that the tower nuns Martha stood North of the Church. From the window opened to a view on Onego lake and forest Poluostrov, located 6 km from tavua.

The parting with her husband and children, scarce food, the situation of the prisoners led to serious illness - epilepsy, as it was called epilepsy before, began to torment the nun Martha. Local residents sympathized with the disgraced boyar and advised to be treated waters source. Water from this spring really has a significant calming effect. As legend has it, she could relieve the suffering and healed the unfortunate prisoner. So this place became known as "the Empress key".

The nun Martha never forgot and thanked the residents tolua after his accession to the throne of her son Michael, the peasants were granted the village, and the priest Ermolai Gerasimov – a small land at the Petrovsky in the churchyard Chelouah.

Now this ancient source is not difficult to find, it is the right of the road Medvezhyegorsk, in front of the village, surrounded by a low wooden fence. The water is crystal clear, making your way through the natural filters of the soil, it is purified and mineralized, oxygenated, which is why it has the softness, amazing taste. Even in an ordinary plastic bottle it fizzes tiny asterisks and very durable, up to 6 months retains its natural taste. But every year, according to local residents, the key is waning, and the water in it becomes less and less.