Clearwater generally means sand over mud - I'd go with river sand.
You can usually get decent sand at your local landscape supply, or pool filter sand from a pool supply store. Home Depot also has some decent natural looking sands. You want something with a relatively large grain size if possible, but it's not too critical.
The "natural tan" on that site is a decent pick....but you can probably spend $5 at a local place instead of 20-30 dollars online if you look around a bit.