Lake Baikal, Siberia, Russia

Historical traditions
The first European to reach the lake is said to be Kurbat Ivanov in 1643.
In the past, the Baikal was respectfully referred to by many Russians as the "Baikal Sea" (Russian: Море Байкал, More Baikal), rather than merely "Lake Baikal" (Russian: Озеро Байкал, Ozero Baikal). This usage is attested already on the late-17th century maps by Semyon Remezov. To these days, the strait between the western shore of the Lake and the Olkhon Island is called Maloye More (Малое Море), i.e. "the Little Sea".