Winthrop Beach is the main beach of Winthrop, Massachusetts. It is located along Winthrop Shore Drive, spanning the roadway. The beach begins off Crest Avenue at an area known as the "Green Bars", named for the green railings along the seawall. The beach ends at the base of Water Tower Hill. The ocean has five wave breakers known as the "Five Sis…Winthrop Beach is the main beach of Winthrop, Massachusetts. It is located along Winthrop Shore Drive, spanning the roadway. The beach begins off Crest Avenue at an area known as the "Green Bars", named for the green railings along the seawall. The beach ends at the base of Water Tower Hill. The ocean has five wave breakers known as the "Five Sisters" offshore to protect nearby neighborhoods from the large swells that occur during storms.