I've gone to carrying a Garmin inReach Mini 2 in their dive housing. I have it in my pocket on every offshore dive with a strobe and storm whistle. It uses satellites for communication, is monitored 24x7 by an emergency command center, and I can also text my location to a number of pre-programmed contacts including my wife who then always knows how to reach those I'm diving with. I can also take it with me when hiking or biking in remote areas.