DENVER (KDVR) — It’s not just you and your luggage that fly on a plane. Airlines constantly ship cargo underneath along with your luggage, which is what makes next-day shipping possible.

But, there are a few things you may not expect to sit beneath you when you’re flying to and from the Denver International Airport.

FOX31 spoke with Southwest spokesperson Dan Landson and Customer Service Manager Chris Rupprecht about what’s usually packed with your luggage under the plane.

Raw fish

Seafood is one of the biggest shipments Southwest brings into Denver. It’s common to ship seafood by plane because it can perish fast. Airplanes are the reason Denver has fresh fish. Along with seafood, Southwest also boards packaged perishables like meat on flights.

There’s no barrier between the luggage and the cargo, but with that being said, every item under the plane is packaged correctly. Southwest won’t accept anything with leaks, smells or that is hazardous and thoroughly checks each package before it boards the flight.

Medical samples and supplies

When it comes to shipping medical samples, driving isn’t the quickest way. Southwest transports drug test samples and COVID testing kits in its cargo.

Along with medical samples and equipment, Southwest also ships organs for transplant. This proves extremely helpful when someone needs an organ donation within hours. On board, there can be a heart, lungs and other body parts that are needed to save someone’s life.

Flowers

A common shipment for Southwest is flowers, especially during the holidays. A few days before Valentine’s Day or Mother’s Day is when Southwest sees an increase in flower shipments. Flowers from Central or South America are usually on board during the holidays.

Hops

Some breweries use fresh hops from different states to make their beer. Hops aren’t a common item to travel with you to Denver because of the high cost to ship them fresh, but it does happen during wet hops season.

When it comes to commercial planes, most of what’s under the plane is luggage. While other companies pack cargo as well, Southwest is commonly used because there are frequent flights to and from the DIA every day.