For customers, ocean freight offers a good many real benefits. In the first place, its cost is extremely low. No other mode of transport offers such an advantage for moving large volumes of cargo. A ship can carry vast amounts, and therefore per ton cargo is decidedly more cheaply transported by sea than air. Secondly, ocean freight is more environmentally friendly in its carbon emissions per ton of cargo when viewed against other modes of transport than air. Thirdly, it has a high level of certainty, because ships can sail whatever the weather and are subject to fewer of the hold-ups which occur in air transport. Finally, with its extensive global coverage, ocean freight can reach places that are unreachable in any other way-- linking markets and opening up world trade.