I have worn this hat surfing in Costa Rica and white water tubing, and it stays on very well.  It really protects my face from sunburn, although I find it doesn't quite cover the tip of my nose (that said, a larger brim would probably not be comfortable while surfing).  The brim does not flop into my eyes, and can be popped up for a better view.  The neck-strap is very comfortable and covers my ears well without deafening me.  All-in-all, I have been really pleased with my purchase.  I do have to wear my hair in a braid or a low bun/pony tail while wearing the hat, because like most hats, it doesn't fit over a high pony tail or bun.  Now I just hope they come out with more styles and colors for women.