Southeastern Massachusetts consists of those portions of Massachusetts located along Buzzards Bay, including the cities of New Bedford and Fall River and their respective suburbs. Despite the location of Cape Cod and the islands to its south, which are the southeasternmost parts of the state, they are not always grouped in this designation. At its broadest definition, it includes all of Massachusetts south of Boston and southeast of Worcester, while at its narrowest definition, it is Bristol County and the Western portion of Plymouth County.

Falmouth ( FAL-məth) is a town in Barnstable County, Massachusetts, United States; Barnstable County is coextensive with Cape Cod. The population was 31,532 at the 2010 census, making Falmouth the second-largest municipality on Cape Cod after Barnstable. The terminal for the Steamship Authority ferries to Martha's Vineyard is located in the village of Woods Hole in Falmouth. Woods Hole also contains several scientific organizations such as the Woods Hole Oceanographic Institution (WHOI), the Marine Biological Laboratory (MBL), the Woodwell Climate Research Center, NOAA's Woods Hole Science Aquarium, and the scientific institutions' various museums. For geographic and demographic information on specific parts of the town of Falmouth, please see the articles on East Falmouth, Falmouth Village, North Falmouth, Teaticket, West Falmouth, and Woods Hole. Falmouth also encompasses the villages of Hatchville and Waquoit, which are not census-designated places and fall within the village of East Falmouth based on postal service.

Vineyard Haven is a community within the town of Tisbury, Massachusetts on the island of Martha's Vineyard. It is listed as a census-designated place (CDP) by the U.S. Census Bureau with a population of 2,114 as of the 2010 census.The area was called "Nobnocket" by the Wampanoag people and was first referred to by the colonial settlers as "Homes Hole," "Homes" from a Wampanoag term for "old man" and "Hole" meaning a sheltered inlet. By the 19th century, it was more commonly spelled "Holmes Hole" after the descendants of John Holmes (1730–1812) who had settled in the village during the second half of the 18th century. The village officially changed its name to Vineyard Haven in 1871. The name Vineyard Haven technically refers only to one section of the town of Tisbury, but the names are used interchangeably and Vineyard Haven is commonly used as a title for the whole town. Vineyard Haven is the main port of entry to Martha's Vineyard and one of the three main population centers (with Edgartown and Oak Bluffs). The Steamship Authority wharf is located in Vineyard Haven where ferries arrive and depart year-round. (A second, seasonal wharf is located in neighboring Oak Bluffs.) The year-round population is only about 2,000 people, but that number increases tremendously in the summer.

Newport is a seaside city on Aquidneck Island in Newport County, Rhode Island. It is located in Narragansett Bay, approximately 33 miles (53 km) southeast of Providence, 20 miles (32 km) south of Fall River, Massachusetts, 74 miles (119 km) south of Boston, and 180 miles (290 km) northeast of New York City. It is known as a New England summer resort and is famous for its historic mansions and its rich sailing history. It was the location of the first U.S. Open tournaments in both tennis and golf, as well as every challenge to the America's Cup between 1930 and 1983. It is also the home of Salve Regina University and Naval Station Newport, which houses the United States Naval War College, the Naval Undersea Warfare Center, and an important Navy training center. It was a major 18th-century port city and boasts many buildings from the Colonial era.The city is the county seat of Newport County, which has no governmental functions other than court administrative and sheriff corrections boundaries. It was known for being the location of the "Summer White Houses" during the administrations of presidents Dwight D. Eisenhower and John F. Kennedy. The population is 25,163 as of the 2020 census.