Since September 11, 2001, restrictions on what can and cannot be brought onto a plane have changed. For one, the Transportation Safety Administration (TSA) has banned blades from being brought on board flights as carry-on items. Today, divers who wish to bring a dive knife on a trip can check the knife with checked luggage, mail the knife to their destination or take advantage of airline services which will send the knife to the destination. Of these, checking the knife is the least costly and most convenient option.
Put the knife securely in a sheath or wrap it up. To wrap the knife, place the blade between two pieces of strong cardboard and tape the cardboard together, then tape the knife to the cardboard so that it cannot slip out. Doing so will ensure that the blade will not accidentally pierce through the side of the luggage or injure an inspector. If this is not done, the knife may be confiscated by the TSA or airline employees.
Pack the knife in the luggage you will check. Make sure that it will not shift around or come out of its sheath or packaging to protect baggage handlers, TSA inspectors and your belongings.
Check in at the airport. You do not need to inform the handlers that you have a dive knife in your checked bag.
Make sure that your dive knife is sheathed securely or packaged so that it will not injure inspectors or baggage handlers.