During a pilot cruise in the Strait of Messina we observed the interface time evolution between Atlantic and Levantine water layers due to semidiurnal tides. Our data are in fairly good agreement with the models computed by Del Ricco (1982) and by Hopkins et al. (1984), as regards long-lasting (1 hour or more) water movements. Quick transient perturbations of columnar shape (probably eddies) which we have called Bignami columns, were also observed and analyzed using both a KODEN fish finder and moored temperature sensors. ¿American Geophysical Union 1987