Near the top of the list of dreamy, bosky local rambles is the 2.5 mile loop around Bon Tempe reservoir on the northwestern slope of Mt.Tamalpais. It is encircled by a deep, cool forest of fir, madrones, redwoods with dense patches of ferns and irises. The lake itself is home to swooping families of mallards, grebes and ospreys. A few choice fishing and picnic sites. Leashed dogs allowed. Park in the Lake Lagunitas lot ($8) and follow the stream below the Lake Lagunitas spillway to a short bridge, then turn right on the next path.