My favorite 5.10 is one I can only climb, well, 50 percent of the time. Two years ago I moved from Colorado to New Hampshire, where you can’t just climb 5.10 in the dry perfection of fall, you have to be able to climb it in the slimy humidity of summer, or when it’s covered with a veneer of ice in the winter. Diedre, a four-pitch line up the middle-right of the soaring east face of Cathedral Ledge, used to be 5.9. Sometimes it feels like 5.11.

I first climbed Diedre in the winter of 2009 with Zoe Hart, visiting from Europe. We wanted a mixed New England classic, and Diedre was iced up and ready, starting with an awkward chimney and giving way to a vertical pillar within a hanging corner. The second pitch was a delicate ice curtain, the third was a gently overhanging, .75-inch steep corner crack, and the topout was a roof move onto a hanging curtain. I told Zoe I couldn’t wait to come back and climb it in the summer, when it was “easy.”

Then summer came. Several summers have in fact come and gone. Diedre has yet to be easy. The first time I racked up for it as a rock climb was with the local Sarah Garlick. I stepped up, grabbed onto holds, and proceeded to drop my backside down low—really low—as if it were attached to two 30-pound sandbags.

It took me another 30 feet to realize what was wrong. Above the first 5.5 section of chimney climbing, a four-foot ice pillar was missing. Because it was July.

“Farrrrrr out,” I said.

“What?” Sarah called up.

I tried to explain. “It’s rock … but I’m climbing ice … or trying to … ”.

“What?”

In that moment, as I meshed two kinds of knowledge, Diedre became my favorite 5.10, and not just because it has one of the best hand cracks at Cathedral. I’ve gone back over a dozen times. Practically every kind of climbing is packed into the route’s pitches. Start with a chimney, move into a short and powerful corner choked with finger jams, and go right. The Diedre traverse is what makes or breaks you. I’ve done it comfortably. I’ve whipped off, too, both leading and following; on rock and on ice. I’ve concluded that you never know what kind of a climbing day you’re having until you attempt to put that sequence of seven moves together.

Diedre is not just my testpiece—it’s an old-school testpiece of the Mount Washington Valley’s. Rick Wilcox, one of the original Cathedral corps from the 1960s and 1970s, owner of International Mountain Equipment in North Conway, and best scoop source for the valley, says: “If you could climb Diedre back in the day, it meant you didn’t suck.”

The route still represents some of the finest climbing on Cathedral.

Majka Burhardt’s newest project is the Lost Mountain in Mozambique.

This article appeared in Rock and Ice issue 216 (February 2014).