Transport by sea is faster and cheaper than the terrestrial. Large-scale maritime trade is carried out by navicularii, shipowners, with representatives in the great ports. Other related professions are negotiatores, specialized merchants like the frumentarii (of grain) or vinarii (of wine). Commercial activity is regulated by law and there are specific taxes for the traffic of goods.
In the great ports are grouped the goods arrived from different points and, from here, boats are chartered again to other secondary ports, generally by means of routes of coasting. In this way the goods of the different points of the Mediterranean are redistributed throughout the territory.
In Republican times, Greece, Carthage and other areas of the Mediterranean maintain fruitful commercial relations, and products such as Greek and Massaliota wine or salted from southern Hispania and North Africa are particularly appreciated.
In imperial times, the Mediterranean is a great market through which products of all the Empire transit. Commerce is mainly produced from the provinces to Rome. Galician and Hispanic wine, Egyptian wheat, oriental fabrics, oil produced in the Guadalquivir valley, saltwater of the Straits area, marbles and luxurious hard stones for the construction of public buildings, spices, slaves ... Gold, tin, lead and silver are exploited.