With its many walking trails, sounds of the Atlantic along the shores, planes flying overhead, and a distinct view of the Boston skyline, Deer Island is one of the most popular recreational areas around Boston Harbor. Today the island is home to the second-largest sewage treatment plant in the United States and is also joined by some of the other surrounding islands to form the Boston Harbor Islands National Recreation Area. However, Deer Island wasn’t always a picturesque and serene location. Much of its history has been filled with tragedy,…