Which material is known for retaining its insulation properties even when wet, making it ideal for warmth in various conditions?

Wool is known for its exceptional ability to retain insulation properties even when wet, which is critical for maintaining warmth in various conditions. The unique structure of wool fibers allows it to trap air, providing insulation, while also being able to absorb moisture without losing its insulating capabilities. This means that even if wool becomes damp, it can still help to keep you warm by preventing heat loss.

In contrast, cotton absorbs moisture easily and loses its insulating properties when wet, making it less suitable for cold and wet conditions. Polyester, while it has quicker drying properties and can insulate well when dry, does not insulate as effectively as wool when damp. Nylon is typically lightweight and water-resistant but lacks the thermal insulation that wool provides, especially when wet. Therefore, wool stands out as the material best suited for retaining warmth under such conditions.