First, this is a pretty good instrument, and the fact it doesn't have the latest and greatest techno-gadgetry incorporated doesn't bother me one wit. My biggest grumble is that the instructions are abysmal and seem to presume that most folks buying the 78sc will be stepping down from a full-feature chart platter rather than buying it as their primary instrument. The online/YouTube instructions aren't any better and seem to assume that folks are spending time in hiking boots rather than deck-shoes -- other than noting the included nautical charts, the writers seem largely ignorant of marine principles. Fortunately I've used a no-frills Garmin 72h with paper charts for sailing for over a decade (and trust it implicitly) and the conventions were similar if not identical. Where the 78sc won me over was running a shallow and twisting inlet on a cold, dark night (where I've previously run aground in a similar situation) and being able to confirm the various buoy lights off the included backlit chart -- for the solo, budget sailor that is pure gold. It picks up satellite signals very quickly and I haven't tested its waterproof abilities, but it seems almost as solidly built as my venerable 72h (which I ran alongside this one, since my initial confidence wasn't high). The trap door for the batteries feels rather clunky compared to the "lesser" 72h which has a solid screw down latch, but overall this is a comparatively sturdy mechanism -- I haven't thrown my paper charts away, however.

Very nice, a lot of function for the money. I spent 6 weeks sailing the Bahamas (Spring and compared the chart quality of this unit to an large chartplotter mounted on my boat and an IPAD loading with the latest Garmin and Navionics charts. The charts on this little handheld were the most accurate! This unit showed individual coral heads correctly. Amazing. Depth contours were more accurate than the others and when we had to navigate through shoal passages, I relied on this Garmin handhold, it was spot on.

I used it in my dinghy and it got wet occasionally. One time I noted the back cover wasn't sealed properly, check it carefully. I ended up with a little fogging in the LCD once in a while but it worked great. I wonder now about long term, as anything in salt water......

I've used a number of Garmin handhelds over the years: aviation, marine, auto. I bought this unit to replace a GPSMAP 76, whose backlight has failed (Garmin refuses to repair). I expected the 78sc to be a decent replacement for the 76. Unfortunately, this is not the case. While the hardware seems very good (bright display, quick satellite acquisition, etc.), the software is just terrible, especially when compared to the old GPSMAP 76.

I tried to use the unit on my sailboat for a little "race around the cans" after downloading all my old waypoints and routes (using Basecamp).

1) After loading up a route consisting of A -> B -> C -> A and starting the the navigation the unit did not flip to the next waypoint, once a waypoint is reached. I could not find any way to manually get it to flip. It's hard to explain clearly, but you will find this very annoying. The GPSMAP 76 was far superior in this regard.

2) Actually, you can't even tell on the navigation page ("compass") what your next point IS. It is not displayed (unlike the 76).

3) The "active route" page gives no information (bearings, distances, etc) about the waypoints of the route, just the names. Again, unlike the 76.

4) When going to a waypoint using "find", the points are listed in order of distance, not alphabetical. If you have a lot of waypoints, this makes it hard to find what you are looking for.

5) The speed and velocity made good jump around quite a bit when you are on a sailboat in moderate seas. The 76 allowed you to smooth out these readings by taking averages over a longer period of time. That option is apparently not available on the 78sc.

6) Unit is hard to read when the backlight is off. With the backlight on, the battery life is poor.

Why did Garmin dumb down the decent user interface of the GPSMAP 76 when it designed the 78sc? A real disappointment. I would say the 78sc is almost unusable for my purposes.

Have read other reviews of this unit, as well. "Cannot Unlock Maps" error. Have owned unit
Update:

Raising to 2 stars because I was able to get the unit working again by downloading the Garmin Express software and performing a re-installation of the existing map (did not need to purchase a new map for $100). Yet, none of this was made clear via the Garmin support site -- needed to figure out on my own.

Recently purchased the garmin 78sc--it worked for 1 week, then got error message (cannot unlock maps), and the unit continued to be inoperable--called garmin after reviewing all negative info on this unit--they said garmin knew about problem and a fix was under way--when reviewing internet info, however, it looks like there have been complaints about this error message for 5 months, and still no fix---they refused to take the unit back, and said replacing it would only give me another bad unit--they said i should wait for a fix and they would contact me----doesn't look like they are too serious about the fix---nothing like sitting around with a brand new unit that doesn't work for an indefinite length of time, with a caeat they they will contact me when they have a fix

shame on you garmin---you used to be a reliable company--one of the benefits of amazon was that i returned it to amazon for a refund
buyers beware!!!!