  The KM3NeT Collaboration has successfully deployed its first detection units
in the Mediterranean Sea in December 2015 (ARCA) and September 2017 (ORCA). The
sample of data collected between September 2016 and March 2017 has been used to
measure the atmospheric muon flux at two different depths under the sea level:
about 3.5\,km with ARCA and about 2.5\,km with ORCA. The atmospheric muon flux
represents an abundant signal for a neutrino telescope and can be used to test
the reliability of the Monte Carlo simulation chain. In this work, the
measurements are compared to Monte Carlo simulations based on MUPAGE and
CORSIKA codes. Measured events and simulated events are treated using the same
approach, making the comparison reliable.
