Spent 2 days at the water park with my grandson and put my M100's in my water shoes. Last visit to the water park I could only be on my feet for about 2 hours until the pain started and limited my activity. With the M100's I had no pain even after 2 days of standing in line for hours and walking several miles around the water park. Made the 2 days much more enjoyable and fun. No adverse effects to the M 100's from the water and they are going back in my hiking boots.