Vitamin D -- specifically the form D3 -- is the only vitamin your body makes itself. It's fat-soluble, which means your body stores vitamin D in its adipose tissue -- in its fat. And, if you want to be specific about things, this vitamin is actually a hormone.
Sullivan's Castle Island, South Boston, MA, Est. 1951. Castle Island. Located at the end of Carson Beach, on Pleasure Bay in South Boston, Castle Island is a 22-acre recreation site, and the site of Fort Independence. Castle Island was really an island until several land reclamations through the years extended causeways and eventually roadways.
Continue walking around the castle, and you'll reach the playground and picnic areas, as well as the main entrance to the fort (summer tours only). Castle Island. There is a crescent-shaped path that stretches out into Boston Harbor and creates an artificial pond known as Pleasure Bay. Many joggers and pedestrians enjoy walking the entire length of the byway, all the way around back to Day Boulevard and the parking lot (about 1 mile).