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Reviews > Stuff Sacks > Dry Bags > Sea to Summit Ultra-Sil Dry Sack > Test Report by Michael Pearl


INITIAL REPORT - June 30, 2011
FIELD REPORT - September 21, 2010
LONG TERM REPORT - November 22, 2011


NAME: Mike Pearl
EMAIL: mikepearl36ATyahooDOTcom
AGE: 37
LOCATION: Woodstock, Vermont, USA
HEIGHT: 5' 9" (1.75 m)
WEIGHT: 155 lb (70.30 kg)

My backpacking experience began six years ago, after years of car camping. Most trips are for two or three days, some lasting a week. I hike with a group of two to four, with plans for a multi-day solo hike this summer. I pack a tent or tarp depending on availability of trail shelters. An average day is 12 miles (19 km). While aware of weight, it is not my primary concern. I strive for enjoyable outings with functional, reliable gear. I usually travel in woodland mountain terrain. I am a three-season camper, but enjoy hiking all year.



Manufacturer: Sea to Summit
Year of Manufacture: 2011
Manufacturer's Website:
MSRP: Not Listed

Listed Weight: 1.4 oz (39.7 g)
Measured Weight: 1.5 oz (42 g)

Listed Dimensions: 8.5 x 21 in (21 x 53 cm)
Measured Dimensions: 8 x 20 in (20 x 52 cm)

Size Tested: 13 L (13.7 qt)
Other Sizes Available: 1, 2, 4, 8, 20, 35 L (1, 2, 4, 8.5, 21, 37 qt)
Color Tested: Sky Blue
Colors Available: Kiwi Green, Sky Blue and Orange

Materials: The body of the bag is made of Ultra-Sil, a 30 Denier siliconized CORDURA nylon with a
polyurethane inner coating. The roll-top closure is a Hypalon strip and plastic side release

-2000 mm hydrostatic head
-double stitched and taped seams, tape sourced from Beamis adhesives, coatings, specialty
films and seam tape company
-high thread count, 240 tpi
-siliconized finish makes packing easy
-non-wicking closure
-very lightweight


The Ultra-Sil Dry Sack arrived in small thin plastic sleeve. Also included was a product information sheet. The information provided is very similar to that found on the website.
Taking the Ultra-Sil out of the packaging was like a magic trick. A very large amount of material emerged from a very small space. The bag is very smooth and slick to the touch and extremely thin and light weight. The stitching is even and straight and nicely taped. The Sea to Summit logo is on one side of the sack. The closure is made of a Hypalon strip on one side. Hypalon is a synthetic rubber noted for its resistance to chemicals, temperature extremes, and ultraviolet light. This material does not wick moisture, helping to keep the sack dry. The other side is a stiff strip of polypropylene. This provides something to fold the sack down on. Just under the Hypalon strip are two small tags. One displays the sack size. The other the fabric brand CORDURA. So far I like what I see; the Ultra-Sil is a well built sack.


A small folding card found in the sack provides instructions in six languages. They are clear and concise. It is noted that the Ultra-Sil is not intended for submersion. Then to close; expel excess air, align top two edges and roll at least three times before securing the buckle.


From the Company Website

-Sack must be closed according to directions to ensure waterproofing. The Hypalon strip should be rolled
down first and have at least three rolls before fastening the buckle.
-Avoid contact with sharp objects or high abrasion surfaces
-double bag any water sensitive devices
-product is not intended for boating or marine use.

From the Product Information Sheet

-same closing technique described
-avoid prolonged submersion
-same precaution regarding electronics
-solvents will damage waterproof coatings and seam sealing tapes. Solvents include DEET and alcohol,
i.e. mosquito repellents and spray sunscreens. Do not write on dry sacks with solvent based permanent
-Frequent washing is advised to prevent embedded fine grain sands from wearing down the fabric. Hand
wash with non-detergent soap and air dry. Do not machine dry. Ensure sack is completely dry before


I put a top and bottom baselayer and a down jacket in the sack. All three items slid in nicely. I folded the closure the recommended three times and closed the buckle. The sack was very balloon like. A large volume of air was trapped inside. So I open it squeezed out the air and re-closed the sack. This worked better making the Ultra-Sil much more manageable. I guess things come with instructions for a reason.
I then went outside and sprayed the Ultra-Sil with the garden hose full blast. The water rolled right off. The contents were completely dry. And a few good shakes and the Ultra-Sil was also relatively dry.
I can't help but wonder if the direction the closure is looped when fastening the buckle matters. After trying it both ways I found it is possible for the sack to unroll once in one of the looping directions. This occurs when I roll the sack down with the Hypalon strip facing me and loop the closure toward myself. Guess it's not a big deal if the sack is rolled four times. But it could affect ability to remain waterproof if only making the recommended three folds.


I will be backpacking in Yellowstone National Park for eight days very soon. I will use the Ultra-Sil Dry Sack to hold my and water sensitive gear. I will be testing for ability to keep my gear dry. Other points of interest are how things will be organized inside the sack, how it works with my pack and durability.


The Ultra-Sil Dry Sack a nice piece of gear. It is well made and easy to use. It provides a high level of water protection at a very low weight. Streams and rivers here I come.

This concludes my Initial Report. In about two month's time I will report again on performance in the field. I would like to thank Sea to Summit and for being able to participate in this Test Series.




Day hike in the rain on Mt. Tom, Woodstock, Vermont
Elevation 700-1,350 ft (213-411 m), temperature 70 F (21 C) and raining

Seven Days Backpacking Yellowstone National Park in Wyoming
Weather encountered; overnight lows around 40 F (4 C) and daytime highs ranged 50 - 85 F (10 - 29 C), one night of rain that began as marble size hail just after dinner. One full day of rain and a second with intermittent showers. The balance was partly sunny to clear and hot.

Terrain traveled; distance 80 mi (129 km), elevation range 7,300 - 8,000 ft (2,225 - 2,438 m), conditions varied greatly from dry hard packed trails to gravelly shoreline to knee deep snow pack to fording waist deep streams.

Three days and two nights in Adirondack Park, New York
Camp - Heart Lake, elevation 2,165 ft (660 m) temperature highs around 75 F (24 C), lows around 50 F (10 C) with light breezes and clear skies
Hike Day 2 - Mt Jo, elevation 2,876 ft (877 m), 2.6 mi (4.2 km) round trip from camp to summit
Hike Day 3 - Marcy Dam, elevation 2,362 ft (720 m), 4.2 mi (6.8 km) round trip from camp to Marcy Lake


My first hike using the Ultra-Sil was to my nearby neighbor hill, Mt. Tom. This was on a morning with a steady rain. The Ultra-Sil held a camera, extra pair of socks, and first aid kit. At the half point of the 8 mi (13 km) hike I stopped for a snack. I quickly checked the contents of the Ultra-Sil. My pack was damp on the inside but all was dry inside the Ultra-Sil. The Ultra-Sil slid easily in and out of my pack. Using the roll top closure and buckle is quick and easy. I did gather a lot of air while closing which made the Ultra-Sil bulky. Upon returning it was still raining. I emptied the Ultra-Sil once indoors and found all items held in the Ultra-Sil to be bone dry.

The Ultra-Sils big trip and mine was to the back country of Yellowstone National Park. On day one an evening shower began with a minute or two of hail. This occurred just as we finished dinner, but before setting up our tent. I was happy this first night when pulling my sleeping gear out of the Ultra-Sil and it was completely dry. Also in the Ultra-Sil on the first day was a first aid/survival kit and small notebook. The rain stopped overnight only to begin again mid-morning. On the second day the rain was steady and lasted several hours. By the time we reached the camp I could feel moisture on the inside of my pack. Spots on the outside of the Ultra-Sil also felt damp. Inside the Ultra-Sil everything was completely dry.

The need to hang food and other odorous items on bear poles in the rain caused me to reorganize my gear. Half the food for this trip was dehydrated at home and held in resealable sandwich bags. I did not want to risk getting any of this food wet. On the second day the sleeping bag, bag liner and pillow came out of the Ultra-Sil and the food went in. All other odorous things went in as well, which was toiletries and hygiene items. I did not want to put too much tension or cause any abrasion to the Ultra-Sil. So before hanging the Ultra-Sil I put it into a nylon mesh sack which was hoisted up the bear pole. Every meal held in the Ultra-Sil stayed dry until it was dropped into the cook pot.

On my first hike I had trouble with keeping air out of the Ultra-Sil while closing it. By the third day in Yellowstone I had perfected my technique. Once all items are in I squeeze the sides of the sack together. Then run my hands up the sack toward the closure. The key is to keep the sides in contact with each other while pushing the air out. Then quickly closing the Hypalon strip and rolling the excess material down. After several cycles I was able to do this in one fluid motion, thus eliminating wasted space in pack.

The last trip during the Field Testing was with the family to the LOJ campground in upstate New York. Not a drop of rain fell the whole weekend. I have never been disappointed that it did not rain before. The Ultra-Sil was still handy. It was very helpful for keeping gear organized and accessible. We used the Ultra-Sil to hold windbreakers and fleece jackets while hiking. This made it easy to get to other things inside our day pack.


The Ultra-Sil has done an excellent job of keeping things dry. In direct exposure to rain or in contact with wet material the Ultra-Sil has kept moisture out. My pack was more organized as all items needing to be hung were contained in one sack. The Ultra-Sil easily packed and unpacked and was very visible in or out of my pack. I had no trouble retrieving items from the Ultra-Sil. Light easily penetrates the sack giving a bright blue sheen to things inside. The Ultra-Sil has worked well for me thus far.

This concludes my Field Report. Please check back in two months for the Long Term Report.
I would like thank Sea to Summit and for making this test possible.



A 10 mi (16 km) day hike on the Appalachian Trail in Vermont.
Weather encountered, temperature of 55 F (13 C) and rainy.
Terrain traveled consisted of mud and rock covered trails, through heavily wooded rolling hills with elevations of 1200 - 2600 ft (360 - 790 m).

Overnight on the highest peak in Vermont, Mt. Mansfield elevation 4395 ft (1340 m). Camped at Taft Lodge at 3600 ft (1097 m).
Weather encountered on Day 1 - Temperature a high of 44 F (7 C) and low of 31 F (-1 C), with a 0.5 in (1.25 cm) of sporadic rain and non-stop fog with light winds turning into 25 mph (40 kph) gust with snowfall at and above treeline.
Day 2 - Temperature a high of 46 F (8 C) and low of 31 F (-1 C), clouds breaking early and skies turning partly sunny with light breezes.

Terrain traveled varied with change in elevation. The trail began in dense hardwood forest with many muddy and root strewn sections. As the trail climbs many areas of large, bare rock slabs are covered, some vertically. Once at treeline following the trail involves scrambling over large rocks and boulders. Nearing the summit the trail crosses the largest of three alpine tundras in Vermont at about 200 acres (81 ha). Here the trail is bare rock, many having very limited traction or wood puncheons.

A 5 mi (8 km) day on the Appalachian Trail in New Hampshire. Weather the day of the hike, 45 F (7 C) and mostly sunny with light winds. The section of trail hiked has an elevation of 500 - 1300 ft (150 - 400 km). A thick layer of leaves covered the trail then changed to pine needles after a steep rocky climb. This was a shorter hike due to my pack load, my 24 lbs (11 kg) three year old daughter.


IMAGE 1On the Appalachian Trail the Ultra-Sil held a cell phone, trail map, first aid kit and a ration of food. I carried the Ultra-Sil inside my small daypack along with a second dry sack. Brief downpours interrupted a day of constant rain. During the hike I didn't use any the items in the Ultra-Sil. Back at the car I used the cell phone to check in at home. There was moisture on the outside of the Ultra-Sil but the phone and everything inside the sack was dry.

On the Mt. Mansfield overnight the Ultra-Sil held my toothbrush/paste, camp towel, lighter, first aid kit, cell phone, and meals (dinner-dehydrated hummus, cous cous and tuna, breakfast-oatmeal, granola and dried fruit). When setting the items out before packing I thought the different shapes, sizes and bulk of the items would be difficult to pack. However the Ultra-Sil is large enough to allow items to be arranged within the sack. After squeezing out the excess air and closing the sack each item stayed in its place.

After hiking all day in various forms of precipitation the outside of my pack was visibly wet when I arrived at Taft Lodge. The outside of the Ultra-Sil was moist to the touch. The contents and inside of the sack remained dry. After emptying the Ultra-Sil and shaking it few times it dried quickly. Before bedding down for the night I wanted to brush my teeth. I put my brush, paste and towel in the Ultra-Sil. Outside the ground was a bad mix of slushy, rocky and wet. Wanting to have my hands free to catch myself if I fell I found a new use for the closure. Instead of holding the closure in my hand, I slid my arm through the loop made by the closure and carried the sack like a purse. While not a major breakthrough it was small moment of enlightenment.

On my last hike during the long term period the Ultra-Sil held an extra layer of clothing and snack bars for my daughter and me. The Ultra-Sil was stowed inside a child carrier until snack time. After eating our snack my daughter enjoyed carrying the Ultra-Sil like a shoulder bag. She really enjoyed helping carrying our load. In doing so she dropped it twice and hit a tree with it once. Examining the Ultra-Sil back at the car, I found it undamaged.


I find the Ultra-Sil to be a great piece of gear. It is very easy to use, very lightweight and very waterproof. I had no worries about any of the gear in the Ultra-Sil getting wet in any inclement weather. I like the bright blue color making it easy to locate, either in my pack or hanging around camp. The Ultra-Sil performed consistently throughout the test series. I cannot find any areas of wear on the entire sack. As of the last day of use it looks just as bright the first day used.

This concludes my Long Term Report. I would like thank Sea to Summit and for the opportunity to test the Ultra-Sil Dry Sack .

This report was created with the Report Writer Version 1.5 Copyright 2011. All rights reserved.

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