ORCA (Oscillation Research with Cosmics in the Abyss) is the low-energy branch of KM3NeT, the next-generation neutrino Cherenkov detector currently being built in the Mediterranean Sea with the aim of measuring the neutrino mass ordering and searching for high-energy cosmic neutrino sources [1]. The ORCA detector will consist of a dense configuration of 115 vertical strings with an horizontal spacing of 20m, anchored on the seabed off the shore of Toulon, France (see figure left). Each string supports 18 digital optical modules with a vertical spacing of 9m.