Sea to Summit Boab -9C/15F Synthetic Sleeping Bag

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The Boab balances comfort with conscious design.

Sea to Summit says: 

The Boab is a great choice for campers and vehicle-based adventurers looking for a roomy, comfort-oriented sleeping bag. A #5 zipper continues through the footbox, and the double sliders mean the zipper can be opened in either direction for ventilation. For the warmest nights, open the Boab flat as a quilt

Our Verdict

The Sea to Summit Boab –9 °C focuses on comfort without overcomplicating things. Its tapered rectangular cut offers generous room to move, ideal for side sleepers or anyone who finds standard mummy bags too restrictive. While not ultralight, the weight feels justified given its warmth and durability.

The shell and liner are made from 50D recycled polyester with a PFAS-free water-repellent finish. Both fabrics are soft to the touch yet feel tough enough for repeated use. Insulation is reliable down to minus temperatures, and the offset synthetic fill does a solid job of minimising cold spots. The full-length zip includes a plough to reduce snagging and allows the bag to compress surprisingly well for a synthetic model.

Double zip sliders run from shoulder to footbox, providing excellent control over ventilation. The ability to open it flat adds welcome flexibility for warmer nights or camp use as a quilt. Thoughtfully designed and sustainably made, it’s a dependable choice for those who value comfort, room to move and simple practicality.

– Reviewed by Ultralight Outdoor Gear

Features

• Bluesign approved, 50D recycled polyester shell with PFC-free DWR. 50D bluesign-approved recycled polyester liner.
• 100% RCS-certified, post-consumer, recycled, multi-denier synthetic insulation.
• Generous, gender-neutral cut offers plenty of room to move – ideal for those who find mummy bags constrictive.

Specifications

• Comfort: -4°C | 25°F
• Lower Limit: -9°C | 15°F
• Fit: Tapered rectangular 

Short

• Weight: 1623g
• Max User Height: 170cm 

Regular

• Weight: 1854g
• Max User Height: 185cm 

Regular Wide

• Weight: 2111g
• Max User Height: 185cm

Long

• Weight: 2106g
• Max User Height: 198cm 

Material & Construction

• Fabric – Bluesign approved, 50D recycled polyester shell, PFC-free DWR. 50D bluesign- approved recycled polyester liner.
• Insulation – 100% RCS certified, postconsumer recycled, multidenier polyester. Offset insulation avoids cold spots
• Zip – #5 Side zipper continues through footbox. Zipper plough, double sliders. #5 half length zipper on opposite side.
• Foot Box – Tapers to foot-end zipper
• Pillow Integration – Hood accommodates Regular Aeros Pillow

Help & advice:

• The Ultimate Guide to Lightweight Sleeping Bags
• Time-Saver Guide to Choosing a Sleeping Bag
• Sea to Summit Sleeping Bag & Quilt Guide
• Sea to Summit Sleeping Mat Guide
• About Sea to Summit