The oldest and deepest lake on the planet, Lake Baikal is visited by thousands of tourists, scientists, and divers every year. It's located 1,500 meters (4,921 feet) above sea level and has a maximum depth of 1,642 meters (5,387 feet).

The lake formed from a rift between two tectonic plates and is seismically active.

Home to more than 2,500 species of animals and plants, of which 80% are endemic, and sheltering 2/3 of the world's population of seals, the lake is a UNESCO World Heritage Site. 

Some of the species of fish you can find here include the Baikal omul fish, Baikal oil fish, nerpas (Baikal seals), golomyankas, Baikal black and white graylings, and Baikal sturgeons, among others.

As for the underwater flora, over 85 species of submerged macrophytes can be found here, along with 400 species of diatom and several green algae species, just to name a few.

During the winter, the lake freezes, making it the perfect ice diving site with outstanding visibility of nearly 100 meters (328 feet). The water temperature is just below freezing, creating magnificent underwater ice hummocks. 

Even during the summer, divers can enjoy exceptional visibility, with water temperature ranging from 4 to 18 degrees Celsius (39-64 degrees fahrenheit). 

Lake Baikal is a favorite spot for technical divers and deep-water divers using gas mixtures. It offers the proper conditions to test new gear and methods of diving., but with careful planning. The conditions here also push the limits of equipment capabilities, which is why special measures such as frost-protecting dive regulators and using cold-water models are in order.