From May 17 to June 6, 1980, "Acushnet" participated in the largest immigration crisis in the history of the Coast Guard, the Mariel Boat Lift from Cuba. The cutter escorted the vessel "Red Diamond" with 800 refugees into Key West. In addition, she assisted 35 boats, aided 120 refugees directly, and fueled two 41-foot Coast Guard boats. For her efforts, the cutter received the Humanitarian Service Award. During its time in Gulfport, "Acushnet" interdicted nearly 200 Cuban and Haitian refugees, retrieving some of them from shark-infested waters.