KM3NeT

KM3NeT (for Cubic Kilometre Neutrino Telescope) is a neutrino observatory under construction in the Mediterranean Sea, which will eventually consist of three Cherenkov detectors incorporating several cubic-kilometers of water, located more than a mile under the surface. They will detect neutrinos by sensing Cherenkov radiation generated as neutrinos pass through the water faster than light's reduced speed within that water. Their large volumes of water give them a better ability to detect and analyze higher-energy neutrinos, which are of research interest. KM3NeT is a collaboration of three pre-existing neutrino-observatory efforts:

• ANTARES (originally for Astronomy with a Neutrino Telescope and Abyss Environmental Research) offshore from Toulon, France. ANTARES has been operational for a decade, offering experience for the KM3NeT effort. The KM3NeT follow-on, essentially a new version adjacent to ANTARES, is called KM3NeT-Fr, its detector named ORCA (for Oscillation Research with Cosmics in the Abyss).
• NEMO (for Neutrino Mediterranean Observatory), a planned neutrino observatory off the coast of Sicily, given the name KM3NeT-It, its detector now named ARCA (for Astroparticle Research with Cosmics in the Abyss).
• NESTOR (for Neutrino Extended Submarine Telescope with Oceanographic Research) a planned neutrino observatory off Pylos, Greece, given the name KM3NeT-Gr.

Detection efforts can begin during deployment, offering early observation with reduced capabilities.

An unrelated Italian neutrino detector is also called NEMO, for Neutrino Ettore Majorana Observatory. It is an underground detector, currently called NEMO-3 after two upgrades, and with a future planned upgrade called SuperNEMO. Despite the term observatory, it is an experiment detecting neutrinos created on-site, specifically an attempt to detect neutrinoless double beta decay, to find out whether neutrinos are Majorana particles.