Sea to Summit Hamelin Synthetic Sleeping Bag

The Sea to Summit Hamelin is a synthetic sleeping bag built for trekking, backpacking, and car camping, with ISO-tested temperature ratings of 30°F (ISO Lower) or 15°F (ISO Lower) depending on the version selected. Revive Loft synthetic insulation (made from 100% RCS-certified post-consumer recycled polyester) retains warmth even when wet, making the Hamelin a strong choice when conditions turn damp. The bag is available in two temperature ratings and two lengths (Regular and Long).

Built to Stay Warm When Things Get Wet

Synthetic insulation has one decisive advantage over down in the backcountry: it keeps insulating when it absorbs moisture. The Hamelin's Revive Loft fill uses hollow-core polyester fibers in three different denier weights, trapping insulating air even in rain, condensation, or high-humidity environments where a down bag would lose loft and warmth. For paddle touring, shoulder-season trekking, or any trip where a dry bag isn't a guarantee, that resilience is the difference between a comfortable night and a cold one.

A Contour Shape That Moves With You

The Hamelin uses a Contour cut, narrower than a rectangular bag and wider than a mummy, that gives side-sleepers room to roll without creating cold spots at the shoulders or hips. A technical hood, draught collar, and internal draught tubes seal in warmth at the head and neck when temperatures drop. When temperatures rise, the Free Flow zipper system gives multiple ventilation options: the left-side full-length YKK #5 zipper runs double sliders through the footbox so the bag can open completely flat as a quilt, while the right-side half zipper lets both arms out without unzipping the whole bag.

Recycled Materials, Verified Standards

The shell fabric and Revive Loft insulation are both made from 100% post-consumer recycled polyester certified to the Recycled Claim Standard (RCS) and approved by bluesign, an independent standard for responsible textile manufacturing. The Hamelin is part of Sea to Summit's 1% for the Planet commitment, with a portion of revenue directed to biodiversity conservation organizations.

Features

• Revive Loft synthetic insulation: hollow-core, multi-denier recycled polyester that insulates when wet
• Free Flow zipper system: left-side full-length YKK #5 two-way zipper with double sliders through the footbox; right-side YKK #5 two-way half zipper for arms-free ventilation
• Contour shape: roomier than a mummy cut, suited to side-sleepers and combination sleepers
• Thermal retention features: technical hood, draught collar, and draught tubes
• RCS-certified recycled materials: shell and insulation both bluesign-approved
• Includes compression sack

Specifications

Who This Is For and Isn't

The Hamelin suits trekkers, backpackers, and car campers who prioritize warmth retention in wet or variable conditions over minimum pack weight. The Contour shape works well for side-sleepers and anyone who finds a mummy bag too restrictive. The 30°F version covers three-season use; the 15°F version extends into cold-weather and winter shoulder-season trips. The Long size fits users up to 198 cm / 6 ft 6 in.

The Hamelin does not include a zipper coupling and cannot be zipped together with a second bag to form a double. It is not designed to attach to a sleeping pad. The Contour width is narrower than a pad-attachment system requires, and the bag would rotate when the sleeper rolls over. Buyers whose primary concern is minimum weight and packed volume for ultralight travel will find the Hamelin heavier and bulkier than down alternatives at the same temperature rating.

Common Questions

Is the Hamelin a good bag for backpacking?

The Hamelin Synthetic Sleeping Bag is a capable backpacking bag when comfort and wet-weather performance matter more than minimum weight. Its Revive Loft insulation retains warmth when damp, and the Contour shape gives more room to move than a mummy bag. Buyers focused on the lightest possible pack weight may prefer a down bag, which packs smaller and lighter at the same temperature rating but costs more and loses insulation value when wet.

What do the ISO temperature ratings mean, and which one applies to me?

Sea to Summit rates the Hamelin using the ISO 23537 protocol, which produces two figures: ISO Lower Limit (the temperature at which a man in warm clothing on a good sleeping pad should stay warm) and ISO Comfort (the temperature at which a woman should stay warm). The 30°F version carries an ISO Lower of -1°C / 30°F and an ISO Comfort of 3°C / 37°F. The 15°F version carries an ISO Lower of -9°C / 16°F and an ISO Comfort of -3°C / 27°F. These are guidelines; actual warmth depends on clothing, sleeping pad R-value, and conditions.

Can the Hamelin be machine washed?

The Hamelin Synthetic Sleeping Bag can be washed in a front-loading machine. A top-loading machine with a central agitator is not recommended, as the agitator can stress the seams and insulation of lightweight sleeping bags.

Can the Hamelin be attached to a sleeping pad?

No. The Hamelin Synthetic Sleeping Bag is not designed to attach to a sleeping pad. Sleeping bags built for pad attachment are significantly wider; the Hamelin's Contour shape would cause the bag to rotate when the sleeper rolls over if attached to a mat.

Can the Hamelin be opened flat as a quilt?

Yes. The left-side full-length YKK zipper on the Hamelin Synthetic Sleeping Bag runs double sliders through the footbox, allowing the bag to be unzipped completely and laid flat as a quilt. The right-side half zipper can also be opened independently to free both arms without unzipping the full bag.