Just because ship can carry nominal value of 15K TEUs, it is very hard to estimate how many containers are currently on board. Also, empty container looks exactly like the full container from the outside, looking at the ship.

One very interesting aspect of ship operations is the art of stowage of containers. The complexity associated with it is substantial. 3D large scale Tetris. This is a good introductory article https://www.shippingandfreightresource.com/container-stowage...

All cargo/intermodal logistics stuff is measured in TEU’s, aka “Twenty foot Equivalent Units”, eg a standard shipping container. The sizes actually vary but for thinking about the numbers, pretend they’re all standard twenty foot containers that you see on trucks.

The average container ship can carry anywhere from 5,000 to 20,000 TEU, with the newer VLCS and ULCS ships carrying up to 25,000 TEU.

That’s 5-25,000 containers on a single ship, and there’s estimated to be around 20,000 container ships currently operating.

Global container trade is somewhere near 1 Billion TEU per year currently.

All of that is ignoring Bulk Cargo such as oil/liquid tankers, dry goods (grains and ores, etc), and other non-containerised goods.

Every single number in this industry is mind boggling.

Might be useful to imagine all the stuff you buy in a year, even well packaged. And now multiply that by amount of people that aren't essentially sustenance farmers...

Now that I think of it, maybe 1 billion TEU is not that much. Single person does not even use full container...

Just remember that for making the final product you buy, there are several "generations" of components that also need to be transported.

> pretend they’re all standard twenty foot containers that you see on trucks.

Just for clarity the standard shipping container we’re all familiar with visually is 40 feet long, and is two TEU’s.