  The non--Gaussian cold spot in the 1-year WMAP data, described in Vielva et
al. and Cruz et al., is analysed in detail in the present paper. First of all,
we perform a more rigorous calculation of the significance of the non-zero
kurtosis detected in WMAP maps by Vielva et al. in wavelet space, mainly
generated by the Spot. We confirm the robustness of that detection, since the
probability of obtaining this deviation by chance is 0.69%. Afterwards, the
morphology of the Spot is studied by applying Spherical Mexican Hat Wavelets
with different ellipticities. The shape of the Spot is found to be almost
circular. Finally, we discuss if the observed non-Gaussianity in wavelet space
can arise from bad subtracted foreground residues in the WMAP maps. We show
that the flat frequency dependence of the Spot cannot be explained by a thermal
Sunyaev-Zeldovich effect. Based on our present knowledge of Galactic foreground
emissions, we conclude that the significance of our detection is not affected
by Galactic residues in the region of the Spot. Considering different Galactic
foreground estimates, the probability of finding such a big cold spot in
Gaussian simulations is always below 1%.
