  Chain of calculations which have to be performed to predict any kind of
signal in a deep underwater/ice neutrino detector necessarily includes the
lepton propagation through thick layers of matter, as neutrino can be observed
only by means of leptons (muons, first of all, due to their large ranges) that
are generated in $\nu N \to l N$ interactions. Thus, the muon propagation plays
a key role when analyzing data and it is important to understand clearly how
transportation part of simulation chain contributes to total inaccuracy of
final results. Here we consider sources of uncertainties that appear in Monte
Carlo algorithms for simulation of muon transport. The trivial but effective
test is proposed to measure the propagation algorithm accuracy. The test is
applied to three MC muon transport codes (PROPMU, MUSIC, MUM) and results are
reported.
