The high cost of oceanographic cruises often makes it advisable to use opportunity vessels for simple measurements, such as determining the temperature of the water column with expandable bathythermographs (XBT). In this work we examine the goodness and reliability of a method aimed at obtaining the maximum possible information from XBT data, and we apply it to the Canary Islands region. It consists in calculating analytic relations between temperature and salinity from historical conductivity-temperature-depth (CTD) data for the region, which are then used to hindcast/forecast the salinity and density distribution, as well as the distribution of other inferred quantities such as velocity. A hindcasting is carried out using direct independent temperature measurements obtained from a hydrographic cruise south of the island of Gran Canaria. At depths greater than 100-150 m the results show good agreement with the calculations obtained from CTD in situ data.