Lake Baikal is a rift lake in southern Siberia. It the worlds largest freshwater lake (by volume), and with a depth of 1642 at its deepest point, it is also the worlds deepest lake. With the purest freshwater on the planet, in many places on the lake, the ice is completely transparent. It has been reported that you can see 40m below the ice in some of these places.
On shore, the lake has many grottoes, that form impressive icicles during winter. During the summer, the beaches are also great for fishing, and river rafting.