The primary tomography data are the full reception window received and stored by the tomography receiver. The processing includes the extraction of the acoustic signal transmitted by the source, the correction due to mooring motion and clock drift. Then, the arrival time of the signal along the different paths have to be identified. Changes in the soure-to-receiver travel time along the different ray path are due to changes in te ocean sound velocity structure, mainly related to temperature. In the Canary basin, due to the strong anomaly produced by the Mediterranean water, we first observe a leading, unresolved packet, followed by a few resolved refracted ray arrivals, and at last some bottom reflected rays.