The Seal Line map case will keep maps and charts secure and dry in a variety of outdoor environments


Material: 12 oz. vinyl

Interior Dimensions:
Small: 6 x 10.5″
Medium: 10 x 14.5″
Large: 14 x 20.5″

The Cascade Designs Seal Line Map Case is a clear waterproof pouch to protect navigation charts, maps, and other documents for outdoor travel: paddling, hiking, climbing, biking, skiing, and more.

After drenched socks and soggy bagels, perhaps the next worst thing to get wet when travelling in the great outdoors is your map. Even as handheld GPS units become more prevalent in the backcountry, smart trippers will still carry a map as a backup navigation device. Charts and maps are hard enough to keep clean and dry in the woods, on the trail, or ski or bike route, but it’s a pretty tall order when kayaking or canoeing. Paddlesports require the contradictory expectations of keeping a map both secure and dry and always visible and accessible. How does the Seal Line Map Case measure up?

First Impressions

Compared to other, more complex weatherproof map cases, with their patent-pending clamping mechanisms and velcro-and-wingnuts closure systems, the unassuming Seal Line Map Case comes across as a bit … well, uncomplicated. It’s really just a heavy vinyl ‘envelope’, closed with a simple zipper-lock seal familiar to anyone who’s ever bagged a sandwich. Bordered on two sides by sturdy nylon webbing, the case features four plastic D-rings for attaching to a kayak foredeck, canoe thwart, or bike handlebars. Slip a trail map, marine chart, or satellite photo into the Seal Line Map Case, zip it shut, and you’re ready for the elements.

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On The Water

Available in three sizes to fit a variety of documents, the Map Case is transparent on both sides. Depending on the scale of the chart, I can often display an entire day’s worth of paddling on one side, then simply flip it over the next morning, eliminating the need for even daily map updating. While the seal is simple to use, it can be difficult to open when wet, mainly because the two edges are too short to easily grasp, especially when wearing gloves.

On hot summer days when the sun beats down on it, a certain ‘greenhouse effect’ can cause water vapor to condense on the inside of the Map Case, obscuring the view of the chart. I’ve taken to slipping a small packet of silica gel—often packed with electronic products to absorb humidity during shipping—inside the Map Case to prevent this interior fogging.

With the Map Case’s corner D-rings, it can easily be lashed or snapped in place; I’ve added a couple of small carabiners for affixing to my deck bungees. Even in the highest winds and deck-clearing waves, the low-profile Map Case holds firm and has never been lost overboard.

In The Long Run

I purchased my first Map Case several years ago, and liked it so much that I bought a few more. In my experience, when you find a bit of gear your truly appreciate, it’s often a good idea to amass a small personal backstock of them, should the manufacturer ever feel compelled to ‘improve’ on an already great design.

Even after many miles of steady use, my Map Case has neither been lost overboard in crashing waves, nor yellowed or faded by pounding sun. On a few occasions, when I’ve forgotten an inkjet-printed topo map in the Map Case for several weeks, I’ve found that the ink has stained the interior of the clear windows; it was easily removed with a mild citrus cleaner.

For ease of use, dependability, and durability, the Seal Line Map Case has proven itself a vital piece of navigation gear, and will keep maps and charts secure and dry in a variety of outdoor environments.

Hits: watertight seal generally easy to open and close, D-rings for solid mounting, clear on both sides for good visibility
Misses: can be difficult to open with gloves, inkjet prints can stain

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