Hydrapak's 2013 Tamarack is a good pack, with most of the standard features you'd expect to see these days.
Unlike on some of the company's older models, the two main cargo compartments are easily accessible via dual zipper closures, allowing them to fillet open for total access to the internal organizer pouches. A fleece-lined media pocket and open-mouthed outer pocket with quick-release buckle round out the pack's 7L storage capacity.
Shoulder strap adjustability is pretty standard, and the sliding chest strap works like a charm. The removable waist strap gets the job done but doesn't look as though it will leave much room for heftier riders.
Speaking of which, the Tamarack's fit seems more suited to average-to-smaller riders, as the pack itself is somewhat short on a longer torso. This means the shoulder straps need to be extended quite a bit in order to stop the waist strap turning into a belly one.
Housed in its own insulated sleeve, the 100oz (3L) reversible reservoir is easy to fill and clean, with a wide mouth opening. In fact, the lightweight, slightly stretchy bag can be turned inside out for cleaning and/or drying.

The Tamarack's hydration reservoir, complete with baffle and quick-release tube
It also features a quick-release tube, and a baffle down the center to help reduce sloshing. The bite valve is lockable and didn't leak during testing, and the tube is housed via a plastic clip on the right shoulder strap. This worked well but can't be switched to the left shoulder strap.
On the trail, the Tamarack performed well in terms of ventilation, comfort, and ease of bite valve access, but left a little bit to be desired when it came to stability. With a three-quarters full reservoir and cargo space at about 50 percent the pack tended to round out a bit, instead of staying flat and conforming to our back.
Riders who tend to ride in wet conditions should note that the 210D Baby Rip Nylon the Tamarack is constructed of isn't waterproof, and the pack doesn't feature any type of rain cover.