Containers come in different sizes, but most are the standard twenty-foot equivalent units (TEU)—rectangular prisms 6.1 meters (20 feet) long and 2.4 meters wide. The first small container ships of the 1960s carried mere hundreds of TEUs; now four ships launched in 2019 and belonging to MSC Switzerland (Gülsün, Samar, Leni and Mia) hold the record, at 23,756 TEUs each. When they travel very slowly (16 knots, in order to save fuel) these ships can make the journey from Hong Kong to Hamburg (via the Suez Canal)—more than 21,000 kilometers—in 30 days.
