Back in 2009 when I started seakayaking, I was looking for a *truly* waterproof gps that floats. Well the only one back then that met the criteria was the Garmin GPSMAP76 series...
Pretty soon after I received the brand new gps I came to the realiziation that despite the wonderful marketing jargon and cool advertising phrases and terms IP68.. etc.. this lil thing isnt going to last in my intended use ie. seakayaking. The lil itsy bitsy rubber gaskets and O-seals just werent very convincing, my late father would have termed it "Mickey Mouse Quality"
. At the time my budjet was bare and time was short, no time to try to find an alternative solution, so I bought a Aquapac "waterproof" bag where the GPS fit snuglly.
December 2016 the particular GPS was still alive and kicking. a couple rubber buttons have started to show some signs of not being very responsive but still do work.. I have gone thru 3 Aquapac bags during the last 8 paddling seasions and I do generally paddle 1500-2000 kms each season...
I have been anticipating that the trusted and true gps may have to be retired sometime soon.. and right now If I'd have to choose a replacement gps.. I would still probably lean towards the modernized version of my old gps , which would be the Garmin GPSMAP 78xx series PLUS a aquapac or similar waterproof baggie.
On the subject of aquapacs: I'm not very convinced about those. The closure system is VERY finicky! During a 2+ week trip water ingress is imminent even if one manages to seal the closure properly every-single-time-day-or-night! I'm prety sure there are better systems out there but I have used aquapacs because the local outdoors/scouts store has a bunch which I can walk into the shop and test fit my gps in them to for fit. If there was some other product other than aquapac available, I would give it a try as well.