The narrow, eel-like shape of the isthmus which is Panama, plus the layout of its network of roads, means that we will be passing through the capital city several times over the next few weeks, and no visitor can come here even once without taking in one of the 20th century’s greatest engineering achievements. Of the several available ways to experience the mighty Panama Canal, the best is reputed to be to pass through the locks on what is known as a transit boat. Be prepared to commit a day to it though: the operation of the locks is a slow process made even slower by waiting for the larger…