The city's natural harbour first attracted the French explorer La Salle, who named the site "The Rapids". The name "Sarnia" was the Latin name for Guernsey in the Channel Islands just off the coast of Normandy, France. The Sarnia port is still an important centre for lake freighters and "salties" carrying cargoes of grain and petroleum products. It is the largest community in Lambton County.
The aforementioned natural port and the salt caverns that exist in the surrounding areas, coupled with the oil discovered in nearby Oil Springs lead to the massive growth of the petroleum industry in this area. Since Oil Springs was the first place in North America to commercially drill for oil, the knowledge that was acquired there and strengthened in Sarnia led to Sarnians traveling the world teaching other nations how to drill for oil. What is now known as the Chemical Valley, located down river of Sarnia proper, once adorned the back of the Canadian ten dollar bill.
