The Ocean Shore Railraod ran from San Francisco down the coast to Tunitas from 1907-1920. When it went bankrupt, there were few remains: the rails were torn up, and the right of way mostly taken over for Highway 1. At the listed coordinates, you will find one of those remains - Montara Station, now converted into a private home.
The station was originally built with two foot thick walls of granite, quarried on nearby Montara Mountain. Several remodels have left only part of this stonework visible.
The final is a film canister stashed a short drive or walk away. The hide is at N 37 32.7AB W 122 30.8CD. To determine the coords, observe the former station before you:
Observe the street number of the building. Subtract the first digit from the last. That is A. Add all three numbers. That is B.
How many vertical boards are there in the front gate of the station's yard (including the post)? That's C.
There's a decorative inset in the stone post near the gate. How many holes in it? Divide by three and that's D.
CAUTION: Do NOT attempt the final as a night cache.