The Baikal Deep Underwater Neutrino Telescope (BDUNT) (Russian: Байкальский подводный нейтринный телескоп) is a neutrino detector conducting research below the surface of Lake Baikal (Russia) since 2003. The first detector was started in 1990 and completed in 1998. It was upgraded in 2005 and again starting in 2015 to build the Baikal Gigaton Volume Detector (Baikal-GVD.) BDUNT has studied neutrinos coming through the Earth with results on atmospheric muon flux. BDUNT picks up many atmospheric neutrinos created by cosmic rays interacting with the atmosphere – as opposed to cosmic neutrinos which give clues to cosmic events and are therefore of greater interest to physicists.