The Stellwagen Bank National Marine Sanctuary is a busy place. Less than 35 kilometers offshore from Boston’s harbor, the waters are a rich fishing ground, a whale migration route, a shipping channel, and a diving locale. Overseeing the sanctuary, which sits at the mouth of Massachusetts Bay, falls to deputy superintendent Ben Haskell, the superintendent, 14 support staff, and two boats. Access to MarineTraffic.com also helps. One day in late April 2017, Haskell was checking the website and noticed 70 boats crammed into the northwestern corner of the sanctuary, moving back and forth in a tight configuration. What the hell is going on, he wondered.