As others note keeping the electronics alive is going to be hard enough, but the "ping back" is probably the hardest bit.
There is no such thing as mobile connectivity in the middle of the ocean, because there are no cell towers, so your only bet is to use satellite hookups.
Satellite connectivity for things like this is pretty good today, with providers like Iridium providing low bandwidth ping services like their Iridium Short Burst Data Service.
You would use something like the Iridium 9603[0] which idles at 34mA and uses 0.8W to send a message.
That is to say it's all definitely doable, but probably not that simple and much much easier to do today then even 10 years ago.
I would think that one hybrid option would be for the balls to enter into a low-power mode when out of cell signal range and simply store their coordinates once ever five minutes. Then when it washes upon the virtual shore, it connects and uploads its track.
What percentage of the coast lines around the world are covered by cell towers, I wonder?
It would be an improvement over having to find them manually, but if you've gone to the effort to engineer an electronics package capable of connecting to a cell tower after years at sea you can probably get it to ping a satellite regularly "for free".
Concerning the Iridium emitter, of course you wouldn't let it idle at 34mA. It would need to be shut down with a mosfet like and only be turned on when needed (twice a week for example)
I agree completely, you'd work out what kind of power budget you have (maybe even monitor it if you are using solar) and phone home as regularly as reasonable.
As others note keeping the electronics alive is going to be hard enough, but the "ping back" is probably the hardest bit.
There is no such thing as mobile connectivity in the middle of the ocean, because there are no cell towers, so your only bet is to use satellite hookups.
Satellite connectivity for things like this is pretty good today, with providers like Iridium providing low bandwidth ping services like their Iridium Short Burst Data Service.
You would use something like the Iridium 9603[0] which idles at 34mA and uses 0.8W to send a message.
That is to say it's all definitely doable, but probably not that simple and much much easier to do today then even 10 years ago.
[0] https://www.iridium.com/products/iridium-9603-3/