Waitresses dressed in neat conductors’ uniforms step gently through the wood panelled interior of the railway carriage and serve us coffee as we glide alongside the waters of the Panama Canal. We are on the 7.15 am Panama Railway Company train and my companion, Stanley Heckadon-Moreno, a 63-year old anthropologist, is proving to be a mine of information about the history of the narrow strip of land that divides the Pacific Ocean and the Caribbean Sea.

I learn about the mule trains and river canoes that once transported Spanish bullion to Caribbean ports and the steam railway that Irish labourers built across the isthmus in the 1850s. But as we get closer to our destination, the decaying city of Colón, Mr Heckadon-Moreno, who is also communications director at the Smithsonian Tropical Research Institute in Panama City, switches from history to nature.