The Aquifer 28 Hydration Backpack is Marmot's largest daypack for long hikes, peak bagging, and ridge traverses. It includes the Marmot's Hydrapak Shape Shift Reservoir hanging inside the pack's sleeve, and there's a magnetic slot on one of the shoulder straps for the bite valve. The Aquifer's suspension system includes Marmot's highly cushioned Ventilated Convective Airflow back panel and a tubular aluminum frame for sturdy, breathable support. The Aquifer is a traditional top loader for easy packing, and there are multiple attachments for trekking poles or ice axes. There's a zippered pocket on the top lid for valuables, maps, and car keys. Marmot added an external stash pocket for quickly accessed items like layers, and the side stretch pockets hold water bottles.