Towards the end of the last decade, the international astronomical community realised that exploitation of the new generation of 8-10-m class telescopes would be hampered unless surveys of the sky with suitable depth were carried out. Deep surveys aimed at the study of distant galaxies require NIR imaging in order to cope with the cosmological redshift of the galaxy spectral energy distributions (SEDs). In 2000 our group started a deep survey in the Ks-band using INGRID on the WHT and Omega Prime on the CAHA 3.5-m telescope. Our target depth is Ks=22 in AB magnitudes. Good La Palma seeing and better noise behaviour allows us to reach this depth in 2 hr exposures with INGRID, the CAHA/Omega data being about 1 mag. shallower for equal exposure times. On the other hand, the wider field of Omega allows a faster coverage of sky area. Our survey, deemed the COSMOS Survey, thus has two depth regimes, KAB=21 on a wide area and KAB=22 on the deeper areas mapped with INGRID.