This is the cypress tunnel at Point Reyes National Seashore, a nature preserve on the California coast north of San Francisco. The tunnel leads to KPH, a ship-to-shore radio station that once broadcast messages to marine craft in the Pacific. KPH stopped operations in 1997, as more sophisticated radio equipment and satellite communications made radio stations like it obsolete. Now it’s one of the unusual features of Point Reyes, open to visitors interested in a glimpse of the past.