The Colón Free Trade Zone is the second-largest free trade zone in the world after Hong Kong, a walled compound at the edge of the city where hundreds of wholesale warehouses sell electronics, clothing, perfume, jewellery, and liquor to buyers from across Latin America and the Caribbean. It processes billions of dollars in goods annually. For most leisure travellers it is more spectacle than shopping destination — the zone is geared toward commercial buyers making large orders, and retail sales to individuals are limited — but if you want to understand what drives Colón's economy, a walk along its perimeter makes the scale clear. Entry requires a passport.