• because it's not touching you and your sleeping bag
    so breathability isn't an issue
    so it can be 100% water proof

    if you pitch it even half-decently not having sides is no disadvantage

  • I must be missing something. I can lie in mine in the rain and be dry. What happens if it's windy and raining with tarp? Rain comes around the sides, no?

  • if it's windy and raining with a tarp, you either:
    pitch it low, aka "storm pitch"
    pitch it side on to the wind and rain, going over you, aka "lean-to"

  • bivvy bags can be good cos they're very light in cuben, and fairly water resistant
    but being in one in the rain is really hell

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