Triple-E vessel Mary Maersk is the largest, most advanced container ship in the world. Mary Maresk is 400 meters long, 59 meters wide and 73 meters high, which can hold 18000 20-foot containers, making it a new world record holder. Triple-E stands for “Economies of scale”, “Energy efficient” and “Environmentally improved”. The name indicates a new class of fuel-efficient container ships with increased intake that are designed for low speeds and low CO2 emissions.