Dependence of atmospheric muon rate on seawater depth measured with the first KM3NeT detection units

KM3NeTis a research infrastructure located in the Mediterranean Sea, that will consist of two deep-seaCherenkov neutrino detectors. With one detector( ARCA), the KM3NeTCollaboration aims at identifying and studying TeV-PeV astrophysical neutrino sources. With the other detector(ORCA), the neutrino mass ordering will be determined by studying GeV-scale atmospheric neutrino oscillations. The first KM3NeTdetection units were deployed at the Italian and French sites between 2015 and 2017. In this paper, a description of the detectoris presented, together with a summary of the procedures used to calibrate the detectorin-situ. Finally, the dependence of muonrate between $2232-3386$ m seawater depth is compared with a parameterisation of the underwater muonflux.