This is one of my favourite motifs. Unfortunately I can't do it from further back, because the willow that once held Patrick's tree fort fell over, and has sprouted a whole new crop of shoots, which blocks the way. I'll see how far I get on this tomorrow afternoon.
Update -2010/09/06 - alas this one will never be finished. I got distracted by the hot weather and warm ocean water, followed by Hurricane Earl which took out some of the trees on the right. Though I do have enough photos & drawings to work this sketch up as an oil this winter