- Lake Chaechist is a sacred lake, the waters of which have special spiritual and therapeutic powers. It is mentioned in the Avesta and Pahlavi texts and the Shahnameh. It is believed to be connected to the Sea Vourukasha.
- It is mentioned in Avestan texts like Atash Nyash, Avan Yasht, Gosh Yasht, Ashishwangh Yasht and Siroza Yasht. It is especially remembered as the place where King Kae Khushru prayed to different Yazads. He also established the spiritual fire Adar Gushasp, the fire which helped him become the king, near lake Chaechist. It was again at lake Chaechist that king Kae Khushru captured and defeated the evil Turanian king Afrasiyab.
- Lake Chaechist, is one of the several lakes mentioned in the Pahlavi text Bundahishn. The Pahlavi Bahman Yasht states that fire Gushasp burns on the banks of Lake Chaechist. It further states that the lake is deep and has medicinal water which drives away diseases.
- In present times, Chaechist Lake is identified with the Caspian Sea, which is the world’s largest lake. It is situated on the Northern border of Iran. It is bounded by Kazakhstan to the northeast, Russia to the northwest, Azerbaizan to the west and Turkmenistan to the southeast. Its waters are believed to have therapeutic qualities and excellent for relieving rheumatism. Lake Chaechist is also identified with lake Urumiyah in northwest of Iran by some scholars.