Each airline is different and the costs listed here were gathered before the COVID-19 related shutdowns and policies so we have no way of knowing what's coming. But, before COVID, Southwest was the cheapest at about $100 and Delta was quite expensive at about $300. However, depending on what level "account" you have with Delta, your Pakayak could fly for free. Alaska Air let you bring it for free. The best thing to do is check with the airline.