Greece has the largest merchant navy in the world, accounting for more than 15% of the world's total deadweight tonnage (dwt) according to the United Nations Conference on Trade and Development. The Greek merchant navy's total dwt of nearly 245 million is comparable only to Japan's, which is ranked second with almost 224 million. Additionally, Greece represents 39.52% of all of the European Union's dwt. However, today's fleet roster is smaller than an all-time high of 5,000 ships in the late 1970s.

What does Greece have the largest of in the world?