Idea by @Owen Hartley

Dipsea Trail from Mill Valley to Stinson Beach if your visitor is fit and game. Seven miles, three steep climbs, ends at the ocean. Catch the West Marin Stagecoach back so you do not have to walk the return. It is one of the oldest trail races in the country and walking it tells you why every step. Pack water; the climb out of Steep Ravine is no joke.