1) Is the deepest lake in the world (5369 feet)
2) Is the oldest lake in the world (over 25 million years old, most lakes don't last over 10,000 years)
3) Is the largest body of freshwater in the world
4) Contains a fifth of the world's freshwater
5) Harbors over a thousand unique organisms that only live in Lake Baikal. A cool example is the freshwater Baikal Seal, which is found nowhere else
In short, it's a really, really cool lake.