Abstract Iceberg transport costs are a key ingredient of modern trade and economic geography models. Using detailed information on Boston’s nineteenth-century global ice trade, we show that the cost of shipping the only good that truly melts in transit is not well-proxied by this assumption. Additive cost components account for the largest part of per unit ice(berg) transport costs in practice. Moreover, the physics of the melt process and the practice of insulating the ice in transit meant that shipping ice is subject to economies of scale. This finding supports, from an unexpected historical angle, recent efforts to incorporate more realistic features of the transportation sector in trade and economic geography models.