I have a Garmin 76CSx and an older Garmin 76. Both have performed admirably. The 76CSx is our main chart plotter. I think the current version is a 78xxx.
P.S. I think they float, but I've never had reason, nor opportunity, to test that -- yet

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The do float...we have both of those models too.
A word to the new 78 series though, we got one of those for my son. It has a REALLY powerful cool new feature - Custom Maps.
Basically you can take any image, link it to real navigation points via some utility and Google maps, then upload it as a "Custom Map" to the GPS.
This means you can upload things like a hand drawn map, a trail map, or a screen shot of a navigational chart or other image. They caution you not to use copyrighted materials and violate licenses etc., but the U.S. Coastal chart are all free which I think violates no ones license to use. You can screen shot a chart from a chart viewer site or OpenCPN then load it onto the device for no charge, which lets you end around the multi-hundred dollar chart chips.
Of course the chart chips are way better, but if you know where you will be going you can get rough charts onto it without one if you don't mind the leg work.
The seems quite accurate if your source material is to scale and you line up the custom chart correctly.
He is very happy with the 78 and likes it better than our 76 series. All of them are under $500.