 He traveled in Greece, Hispania, Italy, Sicily, Dalmatia, Gaul, Liguria, North Africa, and on the eastern shores of the Adriatic.In Hispania, on the Atlantic coast at Gades (the modern Cadiz), Posidonius could observe tides much higher than in his native Mediterranean.He wrote that daily tides are related to the Moon's orbit, while tidal heights vary with the cycles of the Moon, and he hypothesized about yearly tidal cycles synchronized with the equinoxes and solstices.