South Korea's biggest port is running out of room to store shipping containers, said Park Jung-ho, an official at one of Busan's nine operators. The bigger concern is that the boxes are almost all empty.

Container trade at Busan, the world's fifth-largest port, has fallen about 40 percent in recent months, said Park, at Busan International Terminal Co. Even by stacking boxes five deep and leasing a nearby lot, he barely has room for the 31,700 containers that have piled up on his wharves.

"We are spending half of what we earn from our main business for storage space," said Park who is responsible for placement of equipment and containers for the company.