When cloudlike 900-fill down debuted a few years ago, we wondered if the supply would last. It has, and then some. Not only has the number of sleeping bags with the highest-quality down increased, but fill power has been bumped up across the board; 750-fill, once top-tier, is now a starting point for the best lines.
Thanks to featherweight material, virtually every manufacturer now offers bags rated between 30 and 40 degrees Fahrenheit that weigh well under two pounds. You can spend a little or a lot, but add one to your summer kit and leave that bulky bag behind.
Cold-feet fix: Increasing numbers of bags offer ergonomic footboxes that let feet rest naturally, while allowing insulation to drape warmly around them.
Goose down is still the champ when it comes to durability, warmth-to-weight ratio, and compressibility. But synthetic insulation like PrimaLoft Sport has narrowed the gap, making synth-fill bags a good choice for soggy climates and river trips.