Delta will launch Boston-Honolulu and Seattle-Miami service next winter.
The daily, year-round Seattle-Miami flight begins Dec. 21. The route, connecting Seattle with the U.S. base of Delta joint venture partner Latam, will be Delta's 13th serving Miami.
Delta will compete with Miami hub carrier American Airlines and Alaska Airlines, an American codeshare partner that is Delta's primary competitor in Seattle.
Daily, seasonal Boston-Honolulu service will begin Nov. 21 and operate through April 30. Delta will compete on the route with Hawaiian Airlines.
Delta will also add a second daily flight next winter between its Salt Lake City hub and Honolulu, increasing service between those cities to compete with daily Hawaiian Airlines service that will begin in May.
In addition, Delta will add a third daily flight next winter between Seattle and Honolulu, a route on which it competes with Alaska and Hawaiian.
In total, Delta will fly 22 daily nonstops to four Hawaiian destinations next winter, departing from eight mainland airports.