You might consider writing a note, putting it in a bottle, and throwing it into the ocean. People(do) that for centuries, for these and all kinds of reasons. Some messages have made remarkable journeys in bottles through the ages, like the current titleholder for the world's oldest seafaring note. This one was dropped from a German ship into the Indian Ocean in June 1886, only(discover) in 2018 by a woman walking with a friend on a remote beach in Western Australia.
When the note dried, the woman discovered that the message contained the day when it was written, the exact place which it was sent, and who wrote it. it turns out, the bottle was dropped by the captain of a German ship who was investigating ocean and trade routes. He wanted to see where the bottle would end up, so the note asked was reading it to contact the nearest German officials.
Amazingly, researchers were able to identify the note they found the captain's original journal from 1886. One of the entries mentioned a drift bottle (throw) overboard on the very same date, from the exact same site as detailed in the note, and even the handwriting matched!
But the captain wasn't the first person interested in finding out where a bottled message might end up. In fact, the first known message in a bottle (launch) with the same intention. Around 310 BCE, the Greek philosopher Theophrastus dropped several sealed bottles into the Aegean Sea, (hope) to prove that the Mediterranean Sea was connected to the Atlantic Ocean. But is uncertain whether the bottles he dropped ever made their way to the Atlantic.