What's the best jacket for climbing Denali?

A: Marmot's Parbat is a fine all-around down parka. The $299 edition (another model costs $269) comes with Marmot's proprietary MemBrain shell, a water-repellent material that changes its breathability quotient as temperatures drop. In theory, the colder it is, the less it breathes, the warmer you stay. Either model is well made, with 700-fill down, big pockets, and a deep hood. And, it's long enough to keep your butt covered.

A very similar jacket is the Mountain Hardwear Sub-Zero ($295). It uses 650-fill down—really, not that different from 700-fill—and that company's Conduit shell material. And, there's The North Face's Summit Jacket $299. It's similar to both Marmot and Mountain Hardwear in most regards.

Of course, the real sine qua non of down parkas is the Rock & Ice from Feathered Friends. This may be the warmest parka on the planet, with 21 ounces of 750-fill down and a windproof shell with either Epic (a silicon-treated nylon) or PTFE (aka polytetrafluoroethylene, similar in chemical makeup to Gore-Tex). It has a huge hood, a powder skirt, and four big pockets—two inside and two out, with the inner ones sized to hold one-liter bottles—plus mesh gear stowage bins around the waist. I wore this jacket when I went up Denali, and on summit day I basically used it in place of a rucksack to hold mittens, camera gear, food, and water. It's incredibly warm. But, here's the bad news: the Epic shell will set you back $595, the PTFE $650. The lighter Icefall ($385 with Epic shell) is probably a more versatile piece, and still more than adequate for Denali.

Good luck!

Additional resources: Marmot; The North Face; Mountain Hardwear; Feathered Friends.