Today was a chance to explore Cartagena. There was plenty going on, at the main Plaza a few hundred yards from the entrance of the marina was the end of a charity bike ride with hundreds of riders of all ages crossing the line in their green T-Shirts. Later in the afternoon on the dock near a warship was a parade of the Virgin del Ciridad. She is kept in the cathedral and very rarely taken out. The bishop performed a full mass accompanied by 100 priests some of who carried the virgin on their shoulders. We went to the Romain amphitheatre which has recently been fully uncovered. It had been built upon over centuries by churches and other buildings. The Roman organisation and architecture always impresses. After lunch we visited the naval museum and the first submarine built in the 1880s. It was capable of firing torpedoes and going underwater to a depth of 10 metres for 45 minutes. The inventor patented several important new technologies, the use of batteries for power, the filtering of air to remove CO2 and the periscope.