The detection of very high energy neutrinos is a technological challenge which requires a complex network of sensors performing as a huge detector, and a large shield of matter on top of it against the background of cosmic ray muons. ANTARES is at present the largest neutrino telescope in the northern hemisphere and the largest underwater neutrino telescope in the world. It has been installed at a depth of about 2500 m in the Mediterranean Sea, near the Southern French coast. A three-dimensional array of photomultipliers is used to detect the Cherenkov light emitted by neutrino-induced muons. The array consists of 12 lines, each covering a vertical length of about 450 m and equipped with 75 photomultipliers arranged in triplets, plus an additional instrumentation line. The readout electronics is connected to an on-shore laboratory through a 42 km long electro-optical cable. A promising science program is running nowadays by a large European collaboration. The detector design, which constitutes a complex network of underwater sensors, its performance, and the first technical results are presented.
Keywords: Underwater sensor network, ANTARES neutrino telescope, optical modules, calibration systems, data acquisition and communication, deep sea monitoring.