Sea to Summit uses Ultra-Dry Down insulation in all their Down Sleeping Bags. Coupled with DWR coatings on all sleeping bags, a bit of moisture is nothing to worry about. Our PFC-free treatment helps down to maintain 60% more loft, absorb 30% less moisture, and dry 60% faster than untreated down when exposed to wet conditions.
However, if you're dealing with extremely wet conditions, you may want to consider a Synthetic Sleeping Bag as your best option.