Hat Mountain I had heard of, but I was not aware until quite recently that there was a Tunnel Bluffs trail, or that there was a little cabin up there that was being lovingly fixed up. This is why it rocks when your baby sister's boyfriend is the most adventurous person you know; he adventures, you learn.
Anyway, I was not initially clear which viewpoint this trail originated from. I even stopped quickly at the correct one (near Lions Bay but the bridge builder's commemorative sign) but did not spot the trailhead across the highway one time coming back from Squamish. Now I know.
There was one other vehicle at the lookout, and since no one was ogling the view at the time I assumed they were on the trail. I didn't see anyone, but only went to the Bluffs. I did see 2 little lean-tos set up under a tree about 2/3 of the way to the Bluffs.
This trail reminded me at first of Petgill Lake in that you climb up through the forest as the sounds of the highway grow fainter. This trail is really well marked and easy to follow. It is steep at times but there is also a long section of flat close to the bluffs.
All in all, a nice short hike with a spectacular view. I will return to check out the "Hat Hilton" one day, and perhaps Hat itself. My times were 2 hours up and 1 hour 15 mins down.