In 1990, an Australian named Tim Macartney-Snape took a swim in India’s Bay of Bengal, and then he shouldered a backpack to start a long hike uphill. Four months later, hiking from the ocean, through the foothills of the Himalayas, and eventually climbing to base camp on Mt. Everest and up the mountain itself, Macartney-Snape stood on the summit of the world’s highest peak.

The trip, which Macartney-Snape called the Sea to Summit expedition, spawned a company of the same name that designs travel and outdoors gear. The bags, ponchos, backpack covers, pillows and other products from Sea to Summit (www.seatosummitusa.com) were created with the knowledge Macartney-Snape and his design partners gained after years of wandering the globe.

New this year the company has a line of waterproof gear bags that have already garnered a following among backpackers, climbers and adventure racers. The Ultra Sil Dry Sacks are made of silicon-impregnated nylon, and they weigh almost nothing.

At 0.7 ounces, the smallest Ultra Sil Dry Sack has 1 liter of capacity, which is enough room for a wallet, a cell phone, matches, a compass, dry socks and a few other small essentials. Seven sizes — from 1 to 35 liters in capacity — are offered, but the largest Ultra Sil Dry Sack still weighs in at only a scant 2.3 ounces.

All bags in the line have roll-top closures to form a watertight seal. The fabric is soft and slippery, allowing for easy packing in a crowded backpack. Semi-transparent nylon lets you see what’s stored in each sack without opening it up. Prices range from $9 for the 1-liter sack to $30 for the largest model.

Sea to Summit’s eVent Compression Dry Sack is another interesting new product. Made to store a sleeping bag in the bottom of a backpack, the sack has the standard webbing straps and buckles for compressing a sleeping bag down to the size of a cantaloupe.

But what makes the stuff sack unique is its shell, which includes a waterproof and breathable panel of eVent fabric. After stuffing a bag inside and scrunching it down with the webbing straps, the breathable panel of eVent fabric works essentially as a large valve, letting you push out all the remaining air to vacuum seal the bag.

The eVent fabric is air permeable but waterproof, creating a stuff sack that is 100 percent watertight.

Sea to Summit offers five sizes for its eVent Compression Dry Sack, from small summer-weight bags to bulky winter mountaineering cocoons. The stuff sacks weigh between 3.7 and 7.4 ounces, and prices range from $24 for the extra-small model to $40 for the XL.