The UHE neutrino KM3-230213A

Parallel talk presented at the XXI International Workshop on Neutrino Telescopes - Padova 29 September - 3 October 2025 (https://agenda.infn.it/event/44606/) Abstract: The KM3NeT infrastructure comprises two detectors currently under construction in the Mediterranean Sea: KM3NeT/ARCA, designed for the study of high-energy cosmic neutrinos, and KM3NeT/ORCA, optimized for neutrino oscillation studies. The two detectors are already actively taking data and already providing competitive results. Indeed, the highest-energy neutrino ever observed was detected on February 13th 2023 with the KM3NeT/ARCA neutrino telescope. The observed particle was a muon, whose energy at the detector exceeded 100 PeV, likely coming from the interaction of a neutrino of even higher energy. In this contribution, the details of the detection, the data analysis that lead to the determination of the properties of the observed particle, and the studies carried out by the KM3NeT collaboration on its origin are reported.