A rough and ready bivy
The Borealis is a bivi bag for regular use and tough conditions. It’s made from thick rugged durable fabrics which mean that it’s quite heavy and the packed size is quite big. It’s also expensive. There’s ample room for a winter sleeping bag, sleeping mat and other gear inside.
The hood is large and closes with both a wide flap with Velcrotabs and a drawcord so rain protection is good. There’s a long zip that runs partway down one side so getting in and out is easy.
The zip has glow in the dark pullers on the outside but not on the inside, where they’d be more use. The fabric is air permeable so you can seal yourself inside without suffocating. It also means there’s no stuff y feeling inside. The performance of this bag is excellent then.
However the Rab Ascent costs and weighs less and performs much the same. And for most uses a much lighter less costly bag is fine. If you’re not going to sleep out in stormy weather regularly this bag is unnecessary. If you are it’s one of the best around.