Surface mail is a mail delivery system in which letters and packages travel over the surface of the Earth, as opposed to traveling via airplane. It may include shipping by truck, train, or boat. Most companies and governments that offer international shipping have both a ground service and air service. The advantage of this service is that it tends to be less expensive than air-carried deliveries, but this depends on the location the package is being shipped to. The main disadvantage is that it takes longer for a package to reach its destination.
There are many reasons why surface mail is often less expensive than air mail. The vehicles that transport the mail, such as trucks, cost less to operate and maintain than airplanes. It may also be less expensive because most mail is transported this way, so regular transportation routes and schedules are well-established and often automated for maximum efficiency in moving mass quantities of mail. Because of this, the cost-per-piece is generally lower than mail transported by air, which sometimes requires more labor-intensive handling procedures.
Surface mail takes longer to arrive at its destination because trucks and boats travel at slower speeds than airplanes. This mail may also be a lower class than air mail, and therefore lower priority during loading and delivery. For example, if someone sends a package via international surface mail and it has to travel by sea, at some point it will reach the loading docks and be classified according to importance and urgency. Lower-class mail may not be classified as important as other freight, such as perishable food items. Consequently, the mail may sit at the loading dock for several days before it is loaded onto a ship, adding to the overall delivery time.
As more international business mailing is done via air delivery, the shipping rates are being lowered somewhat for this type of service. Surface mail is usually still the most economical means of shipping a package, however. Therefore, as long as a package is not time-sensitive or perishable, sending it by ground will probably save the sender quite a bit of money. In some remote inland areas, surface mail may be the only delivery method available, and in remote island or mountain areas, air delivery may be the only option.