I was doing a short volunteer project on San Miguel Island (Channel Islands National Park) a while back. Only the ranger and I were on the island, and he was called away unexpectedly. Before he left, he showed, and demonstrated for me, the island's SPOT.

Frequently on that island, and others as well in the park, one could be the only person on the island. Even with a radio, SPOT makes sense. I carried the gadget, even tough I was rarely out of sight of the ranger station.

I am put off by the need for a subscription service, and it yet another electronic widget to cart around, but, hey, it is officially endorsed by a federal agency. It is cheaper than losing rangers.