Every trailhead has a logbook. You sign it so somebody knows you were here, where you came from, and where you’re headed. This one is written in disappearing ink — the page drinks your words as you go, and exactly one person reads what it swallowed, the same day you sign.

Prefer a plain envelope? i.am@thegeof.com reaches the same desk. Not sure what you’d even write? Get your position first — the register accepts coordinates.