While looking up Henry Stellwagen on Yahoo! I kept coming across mention of a bank and I thought it was referring to a financial institution and ignored the sites. I eventually arrived at the conclusion that this was a bank in the water, so checked it out.
From the site.
Fishermen had called the Middle Ground for years, but it took Henry S. Stellwagen, a lieutenant-commander in the USN on loan to the U.S. Coast Survey working from the U.S. Coast Survey steamer Bibb to map the entire length and breadth of the bank from 1854-1856.
The bank is located between Cape Cod and Cape Ann in Massachusetts.