Amazon operates its own fleet of jets to deliver packages around the world and get them to customers quicker.
It announced on Tuesday that it is expanding its number of planes, and aims to have 70 by 2021 as part of its bid to complete its own deliveries so it can deliver products to customers in just one day.
It will be adding 15 Boeing planes as part of this, which are older 737-800 planes that have been converted to carry cargo around the world.
Business Insider took a look around a newly converted plane at the Paris Air Show, before it was delivered.
Amazon promises speedy delivery on millions of items, and launched its own airline in 2016 so it could have its own cargo planes to fulfill that promise.
It has expanded that fleet since, most recently with an announcement on Tuesday that it will increase the number of planes it operates to 70 by 2021. It wants to use these to decrease its Prime delivery time to a maximum of one day.
These new cargo planes are actually converted Boeing 737-800 passenger planes, which Boeing calls "BCF"s, or Boeing Converted Freighters. You can see the passenger windows blocked out on the side of the plane.
But Boeing also created a whole new door on the side of the plane to install cargo, which is hydraulically operated.
Crew enter the plane by the smaller side door, where they enter a space between the cockpit and the cargo hold.
The cargo hold is separated from the crew area, but is accessible through a small door. The wall protects the crew from the force of the cargo, in case it moves.
The hold is pressurized, so animals can travel in the space.
The ground is reinforced, and more cargo is stored underneath. It can carry almost 23 tons of freight.
Only two people can enter the area at a time during a flight to handle cargo, including animals and perishable goods like food.
The floor is made up of clips and rollers to move and secure cargo.
Dave Clark, Senior Vice President of Worldwide Operations at Amazon, said that the new planes "create additional capacity for Amazon Air, building on the investment in our Prime Free One-Day program."
This plane originally entered service in 2004, and was recently converted. Alvey Pratt, the director for converted freighters at Boeing Global Services, said the conversion process is "relatively straightforward" and takes around 90 days.
Converting a plane costs around $5 million for planes that don't require additional maintenance or extra features, Pratt said.
Pratt said that a 15 to 20-year-old plane is a good age to convert into a cargo plane, and said that some companies were buying older planes to convert them as a "asset."
He said that this conversion process can "add decades" on to the lifespan of a plane.