On the sea bottom along Slovene Istria coast are among other preserved the foundations of Roman building which stood directly at the coast, and remains of Roman ports. Foundations of the Roman port in Simon’s Bay and in Viližan in Izola were first measured and published by A. Degrassi. As those find are significant for reseaching into oldest naval past of the Slovene part of Istria, the Maritime museum already in 1963 began with underwater researches. The author wishes with the help of documentary materials to present the results of underwater researches in Fižine in Portorož, in Simon’s Bay and Viližana in Izola, that is, give data on major underwater archaeological sites along our coast.