[PeterisP]

GPS trackers are sometimes used, but GPS is receive-only, they allow you to track the location history if you have gotten the container and the tracker; but it does not imply having the ability to locate it if it's lost because the container can't send its location to you from the middle of the ocean - doing that would require essentially having a satellite radio with proper antennas, and that's not generally done. A naval transponder would allow it to be located if you're within perhaps 40 miles or something in the ballpark, but events like this tend to happen much further from a coast.

In any case, that would be worthless, in almost all cases it wouldn't be worth to explicitly go out and retrieve the container even if it would still be undamaged and floating (which is unlikely).