  We have carried out $^{63,65}$Cu NMR spectra measurements in magnetic field
up to about 45~T on single crystal of a multiferroic triangular antiferromagnet
CuCrO$_2$. The measurements were performed for magnetic fields aligned along
the crystal $c$-axis. Field and temperature evolution of the spectral shape
demonstrates a number of phase transitions. It was found that the 3D magnetic
ordering takes place in the low field range ($H\lesssim15$~T). At higher fields
magnetic structures form within individual triangular planes whereas the spin
directions of the magnetic ions from neighboring planes are not correlated. It
is established that the 2D-3D transition is hysteretic in field and
temperature. Lineshape analysis reveals several possible magnetic structures
existing within individual planes for different phases of CuCrO$_2$. Within
certain regions on the magnetic H-T phase diagram of CuCrO$_2$ a 3D magnetic
ordering with tensor order parameter is expected.
