Hackaday.com has an interesting article about some amateur radio technology used in the Thailand cave rescues during summer of 2018.
From the article:
Unless you live in a cave, you’ve probably heard a little about the thirteen people — mostly children — trapped in the Tham Luang Nang Non cave in Thailand. What you may have missed, though, is the hacker/ham radio connection. The British Cave Rescue Council (BCRC) was asked for their expert help. Rick Stanton, John Volanthen and Rob Harper answered the call. They were equipped with HeyPhones. The HeyPhone is a 17-year-old design from John Hey, G3TDZ. Sadly, [G3TDZ] is now a silent key (ham radio parlance for deceased) so he didn’t get to see his design play a role in this high-profile rescue, although it has apparently been a part of many others in the past.
Head over and read the entire article: