The leaders of the packs

Rucksack, knapsack, packsack, haversack. Whatever you want to call it, the backpack is better than ever. With highly engineered back ventilation, quick-access zippered hip pockets, built-in hydration-system compatibility and more, the new packs help keep you cool, well-fed and well-hydrated. Here are four standout models that’ll cover your back on five-hour adventure races, all-day and overnight hikes and multi-day adventures.

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Inov-8 Race Pro 18: Ultralight, frameless day hiking/cycling/running/adventure racing pack designed for a unique horizontal-position water bladder that sits around your hips instead of in the normal straight up-and-down position.

Hip-level hydration

Likes: Very comfortable. Using the optional bladder (which you must buy to make the horizontal format work), you barely feel the water weight. Very convenient waist-belt pockets for on-the-move access to energy bars. Includes 18-liter cargo bay with separate top mesh pocket for camera or other quick-access essentials. 16.5 ounces.

Dislikes: It takes a little extra time to carefully fit the bladder in place after you remove it for cleaning.

Price: $90. Bladder (sold separately), $25. (877) 88-INOV8; www.inov-8.us

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The breeze at your back

Osprey Atmos 35: Mid-size day/overnight pack with unique ventilation, food access pockets and carrying capacity.

Likes: Innovative, practical, comfortable product. Your entire back stays cool against a huge mesh compartment that is created by an internal aluminum frame that props the cargo bay away from your skin.

The space is so huge you could throw valuables or another hydration bladder in it. Great air flow combines with well-balanced 35-liter carrying capacity. Includes massive, zippered, mesh waist-belt pockets big enough to hold fruit, plus a pocket for a hydration bladder (not included) and an access port, four gear loops, lateral stretch pockets for food and hiking poles, and a pair of tie-down straps for a sleeping bag. 2 pounds, 9 ounces.

Dislikes: None.

Price: $159. (970) 564-5900; www.ospreypacks.com

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Light, but heavy on options

Gregory Z-30: Lightweight day or overnight pack for carrying 25 pounds, with ventilated back and hip-belt pockets

Likes: Think of the Z-30 as a budget version of the Osprey, with all the “great” aspects of that product changed to “good”: an effective, back-cooling air-flow design with an internal frame; energy bar-sized zippered hip-belt pockets; a hydration-bladder pocket; and a large top pocket for your camera and essentials. Its 30-liter (1,800-cubic-inch) capacity includes a large external pouch for a helmet, lateral mesh side pockets for food, hiking-pole attachment points for trekking poles, a hydration sleeve and hanger, and a front bucket pocket and side mesh pockets to stuff things on the go all cap off the details on this well-thought-out pack. 2 pounds, 12 ounces (in medium).

Dislikes: No bottom sleeping bag tie-down straps.

Price: $119. (800) 477-3420; www.gregorypacks.com

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Ready for the long haul

High Sierra Sentinel 65: Large, top-loading, internal-framed pack for multi-day backpacking trips.

Likes: Cargo capacity of 65 liters (3,970 cubic inches) swallows big hauls comfortably in four compartments: a main cinch-closure duffel, a large zippered top pocket, a zip-closure rear flap and a bottom sleeping bag trunk with divider. Nice features include a hydration pocket with a hanger clip and a tube port (bladder not included), a chest-harness pocket big enough for three energy bars or a small digital camera, and a pair of grapefruit-sized reach-back mesh pockets that can hold water bottles, a pull-out rain cover, and hiking-pole lashing straps. The comfy padded shoulder harness can adjust 6 inches in height. 4.8 pounds.

Dislikes: No pockets on the hip belt.

Price: Can be found at $130 at retail; $220 on website. (800) 323-9590; www.highsierrasport.com

-- Roy M. Wallack

Irvine-based writer Roy M. Wallack carried a 40-pound pack for eight days in the 400-mile Primal Quest adventure race and is the co-author of “Bike for Life: How to Ride to 100.” E-mail him at roywallack@aol.com.