Don Kaka
The strongest activewear find on this page: yoga and gym outfits cut from 100% non-superwash merino or 100% organic cotton, sewn with cotton thread, and free of polyester, nylon and spandex. Reach for the undyed and plant-dyed pieces first.
Made to order, so plan for a wait rather than next-day delivery.
A US source in the The Second Skin directory. Check that it ships to Europe; where it does not, the directory lists a European alternative alongside it.