With the DryPak phone cases, you can actually use your cell phone while it remains protected in this tough (and bouyant) bag.  Simply place your phone or other items inside, twist the knobs and seal out water, sand and dust.  Floating bag has a yellow sealing clip for high visibility.  It's also great for securing your other small valuables, sensitive materials, toilet paper etc. for trips on and in the water.  Made from durable clear heavy gauge vinyl.  Available in 2 sizes to fit your exact need.  Includes a lanyard and clip to secure to you or your boat.