In 1575, Sir George Bruce of Carnock of Culross, Scotland, opened the first coal mine to extract coal from a "moat pit" under the sea on the Firth of Forth. He constructed an artificial loading island into which he sank a 40 ft shaft that connected to another two shafts for drainage and improved ventilation. The technology was far in advance of any coal mining method in the late medieval period and was considered one of the industrial wonders of the age.