A really comfortable fitting boot in the shop turned into a mini-nightmare when put to the test of a five day walk. Across the granular environment of the Fish River Canyon sand filtered into the mesh covered tongue and got between the inner lining and upper where more and more became become trapped. After two days this caused increasingly painful pressure on the toes. Initially I assumed my feet were swelling. They weren't: the shoes had bulged with trapped sand.  When I tried to dislodge the sand it just spread around between the rest of the lining. On probing between tongue and lining my finger slipped through.  (picture of just some of the sand that came out of the shoes' lining)  That it happened to both shoes suggests it is not just a faulty item, but a design flaw. It probably means the same thing happens with water; this site has a number of complaints about waterproofing issues on these shoes.  What it also means is that this model of shoe does not appear to have been properly tested. Or if they have, then the company has ignored the results.  The company care and maintenance literature was of no help. Contact with the company proved to be a drawn out process with no results.