Pictures by Dave.

Dave Gedye is in town for my 60th birthday party, and we decide to do the Diablo Reference Hike the next day. That's where I see how old I'm getting.

We're on the trail at 11 AM. It's a warm day - mid-70s, feels hotter in the sun. Dave - who's in great shape from trail-running - wants to break my ascent record of 2:01, set in 2013. But at Murchio Gap we're 5 min off that pace, and sagging a bit, so we take a 10 min break and proceed at a quick but not frenetic pace. Dave has a new watch that computes instantaneous rate of elevation gain, among other advanced performance metrics. I'm suffering from lack of sleep and semi-fatigue, and my legs feel kind of heavy. We're at the summit in 2:29:50.

Dave revives the issue of surface-area visibility. The vistor center claims only that Diablo is the max among parks in the lower 48. Dave asks if there is an efficient algorithm for computing visible area from height data; the obvious algorithm is O(N^2) at least.

We get Gatorade at the visitor center and sit around a while.

We decide to try for a descent record, which is easier since I've never tried to go fast. We crank out a number of miles in the 20-22 minute range, and make it to the bottom in 1:57, which I think is a record (for me) by a wide margin.

Injury report: sore toes.

Bonus pictures! From the night before, when a group of us, after my BDay party, climbed to the top of Yerba Buena Island.