In a recent survey at 33 GHz for baryonic matter at large scales in the Corona Borealis Supercluster (CrB-SC) of galaxies (z = 0.07) using the Very Small Array interferometer (VSA), covering 24^2, two strongs decrements in temperature (CrB-B and CrB-H) near the centre of the supercluster were detected. The amplitudes are -157+/-27 and -230+/-23μK for decrements CrB-B and CrB-H respectively. There are no known clusters of galaxies coincident with the position of either of these decrements. Monte-Carlo simulations show that only CrB-B can be produced by primary anisotropies in the Cosmic Microwave Background (CMB) radiation. To explain the origen of CrB-H, a combination of both CMB perturbations and the Sunyaev-Zel'dovich effect (SZE) is required. We explore the possibility that this SZE could be produced by warm/hot gas on superclusters scales. ROSAT images do not show X-ray emission in these regions. We study the distribution of galaxies down to r ≤ 20 magnitudes in CrB-SC. Our analysis reveals in the region of CrB-H an overdensity of galaxies by a factor of two with respect to nearby control fields. No evidence for a new cluster is found, but the presece of a large number of galaxies in the intercluster region is suggestive that associated gas could be at least partially responsible for the observed temperature decrement in the CMB signal. We obtained spectroscopic redshifts for a sample of these galaxies and found first evidence for a substructure in the spot region extending from z = 0.07 - 0.09. This is suggestive of a dense filamentary structure of size several tens of Mpc.