Why would transporting goods by sea have been preferable to transportation over land?

Transportation over sea is generally less expensive and more direct. Furthermore, marine transport tends to be more energy efficient and safer than rail or road transport. A recent study (December 2007) by the Texas Transportation Institue, Center for Ports and Waterways (tti.tamu.edu). For instance, ton-miles traveled per gallon of fuel is 576 for barge; 413 for rail; and 155 for semi-tractor trailer. self-propelled vessels even beat the barge numbers. Furthermore, the ratio of highway and rail to inland marine fatalities is 155 to 22.7 to 1, respectively.