Garmin GPSMap Marine GPS Reviews

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Garmin GPSMap 421

garmin gpsmap 421

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A major leap forward as far as technology is concerned when you are talking about the Garmin GPSMap product line, the 421 comes complete with a fishfinder, the ability to include coastal maps, a transducer, in land maps, and a 4 inch liquid crystal display in stunning color and high definition.

Garmin GPSMap 740

garmin gpsmap 740

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Basically the “new kid on the block” when it comes to Garmin GPSMap units, this is the ultimate marine focused GPS unit on the planet today.

Absolutely loaded with special features (including chart plotting technology, depth sounding technology, fish finding technology, coastal maps, in land maps, transducers, and a whole bunch of other extras – not to mention underwater topography maps), there’s nothing else out there quite like the 740.

Garmin GPSMap 162

Garmin GPSMAP 162 4.2-Inch Waterproof Marine GPS and Chartplotter

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One of the original few Garmin GPSMap units, this is still a viable option for those that need an inexpensive GPS that can get them from Point A to Point B out on the water. Very user-friendly, it has a liquid crystal display in black and white that shows you all of your data up front, and while it isn’t exactly the fastest thing on the planet it’s definitely more than enough to get you up and running without setting you back more than a few hundred dollars.

General Introduction

When most people think of GPS units, they instantly think of the Garmin brand.

Early pioneers of the commercially available GPS unit technology, Garmin has established a reputation for producing high and technology that is as accurate (or more accurate) than anything else out there and packing more technology, features, and innovations into their units than anybody else – while charging less for their products!

Probably more well-known for their hiking, outdoor expedition, geocaching, and vehicle navigation GPS units than anything else, Garmin also makes an incredible lineup of marine focused boat GPS units as well.

The Garmin GPSMap Marine GPS products stable is probably the best of their boat focused units, and they are some of the best products money can buy today. They aren’t the only kind of marine GPS units on the market right now, but it’s hard to imagine any competitor offering anywhere near the kind of technology, special features, and price point that Garmin GPSMap solutions do.


When you’re talking about a GPS unit for your boat that offers:

  • A dedicated multi-satellite (24 or more) GPS receiver
  • WAAS enabled GPS reception technology
  • The ability to create 500 or more unique waypoints and plot courses to each
  • The ability to create 20 reversible routes (with up to 30 individual waypoints) and store them on the onboard memory
  • And the capacity to add as many third-party maps as you wish

…you’re talking about a very special piece of GPS technology.

But you’re also only talking about the Garmin GPSMap product line.

Garmin spared absolutely no expense when it came to designing, developing, engineering, and producing their amazing and breakthrough features for their GPSMap product stable. Garmin understands the importance of the marine market for GPS devices very well. Each and every single successive model has only gotten better than the one that came before it, and that’s because Garmin engineers working on this product line have been in power to make it the best in the business – and never settle for second place.

That means that these Garmin GPSMap units were the first ones to feature 100% full-color displays, high definition resolution units, touchscreen control systems, almost infinite waypoint plotting technology, sonar connectivity (as well as easy integration to numerous marine focused and boat life accessories), and so much more!

You aren’t just purchasing a Garmin GPS unit that can get you to your favorite fishing hole and back without getting lost out on the water – you are purchasing a Garmin GPSMap that can completely change the way you use your boat forever!

Form Factor

Most of the Garmin GPSMap units are easily mounted to the control module and steering system of your boat. This allows them to be right up front and center where you need them most when you are piloting and navigating your boat, but also has allowed the engineers behind these devices to play around a little bit with their form factor.

Some of the units are a little bit on the larger side of things without compromising your field of view, offering screens that are anywhere between 4 inches and 7 inches (or more) so that you can really get an idea as to what your surroundings out on the water. On the other hand, some of these GPSMap units are much, much smaller – designed for heads-up information only while still allowing you to dig deep into more granular data with an intuitive control system.


Any time you are talking about the ability to connect to 24+ individual global positioning satellites miles and miles above the earth 24/7, 365 you are talking about a ridiculous level of navigating accuracy that you just won’t find anywhere else.

Garmin has always been a leader and pioneer in improving GPS technology (especially on the commercial front), and have done absolutely everything they can to increase the accuracy of their devices. To find any Garmin GPSMap unit that doesn’t promise 3 meter (+/-) accuracy is almost impossible, and that’s just thanks to the tight integration of each and every accuracy improvement the company has ever made into these products.

With a Garmin GPSMap, you would be able to find a needle in a haystack underwater if you wanted to!


Understanding that marine-based models are going to require a very specific approach to waterproofing, weatherproofing, and even protection from exposure to long periods of sunlight, the Garmin team has created a unique enclosure and mounting system that protects your GPS from all elements – natural as well as human.

This is going to be a device that is next to impossible to crush, triple, or maim – no matter how hard you might (inadvertently) try! Garmin GPSMap units are survivors through and through, and it’s likely that you’ll end up replacing your boat before you replace your GPS.

Final Verdict

The final verdict of this GPS review is that you’ll definitely have options when it comes time to buy a Marine GPS unit for your boat.

However, if you are looking at anything other than a Garmin GPSMap Marine GPS you’re wasting your time (and possibly even your money). There’s a reason why these Garmin GPS units are bestsellers year in and year out!