ORCA (Oscillations Research with Cosmics in the Abyss) is the low-energy branch of KM3NeT,
the next generation underwater Cherenkov neutrino detector in the Mediterranean. Its primary
goal is to resolve the long-standing unsolved question of whether the neutrino mass ordering
is normal or inverted by measuring matter oscillation effects with atmospheric neutrinos. The
ORCA design foresees a dense configuration of KM3NeT detection units, optimised for studying
the interactions of neutrinos in seawater at low (< 100 GeV) energies. To be deployed at
the French KM3NeT site, ORCA’s multi-PMT optical modules will exploit the excellent optical
properties of deep seawater to accurately reconstruct both cascade (mostly electron neutrinos)
and track events (mostly muon neutrinos) with a few GeV of energy. This contribution discusses
the potential of the ORCA detector both in neutrino mass ordering studies and in obtaining new
constraints on other key parameters such as theta_23. New sensitivity studies of exotic oscillation
phenomena such as sterile neutrinos and non-standard interactions are also presented