Our own time capsules have been intentionally (and legally) placed in regions that force an outdoor commitment.
Small, concealed caches are now spirited away in spectacular mountains of Idaho, along the Pacific Coast of Washington, and somewhere in the undiscovered wilds of Montana. But there are closer places as well.
The hiding of time capsules as a fun adventure will appeal to outdoor enthusiasts of all stripes: geocachers, future explorers, scavenger hunters, or even casual adventurers.