The nation borders Mali in the east , Guinea-Bissau in the south , and Guinea in the south-east . The Gambia is another country inside of Senegal , along the Gambia River . Senegal is externally bounded by the Atlantic Ocean to the west , Mauritania to the north , Mali to the east , and Guinea and Guinea-Bissau to the south ; internally it almost completely surrounds The Gambia , namely on the north , east and south , exempting Gambia 's short Atlantic Ocean coastline .