  We conduct an intensive study of the rich, X-ray luminous, and hot galaxy
cluster Abell 697 (at z=0.282), likely containing a diffuse radio emission, to
determine its dynamical status. Our analysis is based on new spectroscopic data
obtained at the TNG telescope for 93 galaxies and on new photometric data
obtained at the INT telescope. We combine galaxy velocity and position
information to select 68 cluster members, determine global dynamical
properties, and detect possible substructures. The investigation of the
dynamical status is also performed by using X-ray data stored in the Chandra
archive. We compute the line-of-sight (LOS) velocity dispersion of galaxies,
sigma_v=1334 km s^-1, in agreement with the high average X-ray temperature
T_X=10.2 keV recovered from Chandra data. Assuming that the cluster is in
dynamical equilibrium and mass follows the galaxy distribution, we find that
A697 is a very massive cluster obtaining M(<R_max=0.75 Mpc h^-1)=9.5x10^14
solar masses h^-1 and M(<R_vir=3.85 Mpc h^-1)=4.5x10^15 solar masses h^-1 for
the region well sampled by the spectroscopic data and for the entire virialized
region, respectively. Further investigations find that A697 is not fully
relaxed, as shown by the non Gaussianity of the velocity distribution, the
elongation of the X-ray emission, and the presence of small-size substructures
in the central region. Our results suggest that we are looking at a cluster
undergone to a complex cluster merger occurring roughly mainly along the LOS,
with a transverse component in the SSE-NNW direction. Our study supports the
hypothesis of a relation between extended radio emission and merging phenomena.
