  A3667, a spectacular merger cluster, was observed by Chandra twice. In this
paper we review the main results of the analysis of these observations. In
particular we show evidence for the presence in the cluster of a 300 kpc
Kelvin-Helmholtz hydrodynamic instability. We discuss the development of such
instability and the structure of the intracluster magnetic filed in light of a
self-consistent cluster dynamical model.
