  We perform a study of the ultra high energy neutrino detection performances
of a km^3 Neutrino Telescope sitting at the three proposed sites for ANTARES,
NEMO and NESTOR in the Mediterranean sea. We focus on the effect of the
underwater surface profile on the total amount of yearly expected tau and mu
crossing the fiducial volume in the limit of full detection efficiency and
energy resolution. We also emphasize the possible enhancement of matter effect
by a suitable choice of the geometry of the Telescope.
