Thank you all for your responses and insights.
I should have been more specific.
I'm looking for a hand-held waterproof GPS-Radio combo that will work with marine and Coast Guard frequencies and have a power of 10-15 miles.
I'm a scuba diver and, in light of recent tragedy in Egypt where divers from Russia and Holland were lost at sea in early January , decided to invest into a unit that I would be able to use in a pinch (hope to never need to use it). Goecaching also seems like a fun thing to do, especially since there are scuba-specific caches.
I understand that these units have only a limited pressure rating and plan to keep it in a waterproof container rated to a specific depth.
Uniden Mystic that Xlobsterman recommended seems to fit the bill.
How is the Mystic for street navigation?
Thanks again.