Dwr, Dwfr, water - Glyndwrdu, the patrimony of the celebrated Owen Glendower, of which his Anglicized name is a corruption.
We came out through Cwm Dwr which had some beautiful pristine white flowstone that nobody remembered seeing before.
If you need to revive the layer designed for repelling water (the Durable Water Repellent, or DWR, breaks down over time), drying or tumble drying should work.