Facts and rumors...
Mount Teneriffe is a mountain that I have long avoided. Its summit never appeared that attractive, and the only route I was aware of is14 miles round trip...way too long for a mountain under 5000'. The long route, begins at a gated road 1.1 mile past the new Mount Si trailhead at c950' on Mount Si Road and follows the road to the saddle between Mount Si and Mt. Teneriffe before becoming a ridge line trail. Ah, but then a rumor of a shorter, steeper route drifted my way. The rumor was that the route began at the same location as the long route, but followed the road only about one mile before a trail left the road at the first stream crossing.
The rumor I am spreading...
If one was to following the gated road, keeping left at the fork, to the first small stream, you will probably find a path along the stream. Following this path along the stream you might ascend into the forest on slippery moss covered rocks and over trees to a fork at c1600' (the right fork of the path may connect to right fork of the road but seems to offer no advantage). The left fork of the trail will likely continue along the stream over rocks and trees to what could be a tall cascading waterfall. It seems appropriate that there would be a side trail leading to the fall at c2300', maybe midway up the falls. The main trail will probably continue steeply upward, eventually making its way to the crest of a NNE running spur at an elevation of c2850'. It would seem likely that the path would then follow this spur, which could be quite narrow and would probably include some easy scrambling on moss covered rocks just as you started up it. These rocks would almost certainly be slippery if they got wet. As with many non-maintained trails on spurs such as this one, it would basically follow the crest and would become a bit difficult to follow before traversing left around a rocky outcropping near 4500'. Once around the rocky section it would of course regain the crest of the spur and continue to the summit. The summit of Mount Teneriffe is probably little more than a grassy high point with a steep NW side on the long ridge that stretches NE from Mount Si along the Middle Fork Snoqulamie River Valley.
It sounds like this might be a good winter training type of trail, ideal for keeping (or getting) in shape for those spring and summer hikes and climbs. One day, I just might have to go see if this trail really exists.. Maybe it will be sunny and I will remember to bring a camera along to take some pictures...if this trail is more than just a rumor.
Long Route: Hiking the Mountain to Sound Greenway; Harvey Manning; pages 105, 112-114