  The measurement of the individual charged particles especially muons in an
extended air shower (EAS) resulting from primary cosmic rays provides important
distinguishing parameters to identify the chemical composition of the cosmic
primary particles. For Neutrino Telescope experiments like Baikal-GVD, the
estimation of underwater muon flux is of importance to study atmospheric muons.
In this paper, a GEANT4-based simulation is presented to estimate the
atmospheric muon flux underwater taking Baikal-GVD as an example. The location
of the Baikal-GVD experiment at Lake Baikal provides a unique opportunity to
study the passage of muons through its northern shore and the water. The muons
arriving from the north direction will lose more energy as compared to those
arriving from the south. An approximation for the northern shore is also
simulated in the GEANT4 geometry and the results of the simulation are compared
with the measurements from the NT-96 detector. The results of the simulations
are consistent with the shore shadow observed in the measurements in the NT-96.
This approach can also be used to propagate the muons from generators like
CORSIKA through long distances in matter like water, ice, earth, etc. for
simulations in such experiments.
