PT Journal AU ANTARES Collaboration (Ageron, Mea Aguilar, JA Bigongiari, C Carmona, E Dornic, D Emanuele, U Gomez-Gonzalez, JP Hernandez-Rey, JJ Mangano, S Real, D Roca, V Salesa, F Toscano, S Urbano, F Yepes, H Zornoza, JD Zuñiga, J TI ANTARES: The first undersea neutrino telescope SO Nuclear Instruments & Methods in Physics Research A JI Nucl. Instrum. Methods Phys. Res. A PY 2011 BP 11 EP 38 VL 656 IS 1 DI 10.1016/j.nima.2011.06.103 LA English DE Neutrino; Astroparticle; Neutrino astronomy; Deep sea detector; Marine technology; DWDM; Photomultiplier tube; Submarine cable; Wet mateable connector AB The ANTARES Neutrino Telescope was completed in May 2008 and is the first operational Neutrino Telescope in the Mediterranean Sea. The main purpose of the detector is to perform neutrino astronomy and the apparatus also offers facilities for marine and Earth sciences. This paper describes the design, the construction and the installation of the telescope in the deep sea, offshore from Toulon in France. An illustration of the detector performance is given. ER