A recent oceanographic cruise of the Spanish research vessel, B. O. Cornide de Saavedra, provided a suitable platform from which to survey ship traffic through the strait of Gibraltar covering several days. This was long enough for a representative sample to be taken, 472 ships. It was observed that only 65 per cent of the ships passing through the strait observed the traffic lanes. The current structure of the Alboran Sea may offer economic advantage to a different traffic convention. The present mean traffic is 5·8 ships per hour which represents a density greater than that of the Strait of Dover. This suggests that traffic regulation, in the interests of preventing loss of life and oil spills, may be necessary in the near future, particularly when the Suez Canal has been opened to larger tankers.