Key carriers on the Boston (Logan International Airport (BOS)) to Reykjavík (Reykjavík International Airport (REYK)) route in December include Icelandair, PLAY, and select partner/seasonal services. Icelandair: typically offers full-service amenities, free checked bag on some fare classes, frequent flights, and a robust transatlantic network; ideal for flexibility and connections. PLAY: low-cost carrier with competitive base fares in December; lower base fares but pay-per-service model for baggage and seat selection. Partner/seasonal carriers (e.g., Delta codeshares) may offer occasional direct flights—check baggage inclusions and change policies. When comparing, evaluate total trip cost (fare + baggage + seat fees), schedule convenience, and cancellation/change flexibility for winter travel.