The document discusses refrigerated cargo ships (reefer vessels) that transport perishable goods like fruit, vegetables, fish, and meat. It describes the types of reefer ships, their specialized equipment and designs to maintain precise temperatures and atmospheres. Modern technologies like controlled atmosphere systems use inert gases to slow ripening and inhibit pathogens, extending shelf life during transport by weeks. Precise monitoring and control of oxygen and carbon dioxide levels is required to prevent cargo from perishing.