  After a long R&D phase to validate its detector concept, the ANTARES
(Astronomy with a Neutrino Telescope and Abyss environmental RESearch)
collaboration is operating the largest neutrino telescope in the Northern
hemisphere, which is close to completion. It is located in the Mediterranean
Sea, offshore from Toulon in France at a depth of 2500 m of water which provide
a shield from cosmic rays. The detector design is based on the reconstruction
of events produced by neutrino interactions. The expected angular resolution
for high energy muon neutrinos (E>10 TeV) is less than 0.3 deg. To achieve this
good angular resolution, severe requirements on the time resolution of the
detected photons and on the determination of the relative position of the
detection devices must be reached.
  The full 12-line detector is planned to be fully operational during this
year. At present (April 2008) there are 10 lines taking data plus an
instrumented line deployed at the edge of the detector to monitor environmental
sea parameters. This paper describes the design of the detector as well as some
results obtained during the 2007 5-line run (from March to December).
