The origin of the name of the lake is definitely not established. The most widespread versions of an origin of a toponym "Baikal" are given below:
Bai Sack (Turkoman.) — rich lake
Baygaal-Dalai (монг.) — rich fire
Beng-Hai (whale.) — North Sea
The first Russian zemleprokhodets of Siberia used the Evenki name "Lama" (sea). From the second half of the 17th century Russians pass to the name accepted at the Buryat — "Baygaal" (it is said as "Beygkhel"). At the same time they have linguistically adapted him for the language, having replaced characteristic for the Buryat of "" on more habitual for Russian "to" therefore there was finally a modern name.