When you're picking marine electronics sonar navigation gear, the decision often comes down to two very different Garmin tools: a dedicated fishfinder depth sounder and a floating handheld GPS. The GARMIN Fishfinder Depth Finder 80 gives you live sonar for finding fish and reading bottom structure, while the Garmin GPSMAP 79s keeps you on course with waypoints, built-in sensors, and a rugged floating case. Here's how they compare and which one belongs on your boat.
Quick Verdict
If your priority is finding fish and reading depth under the boat, the Fishfinder 80 is the clear pick. If you need a portable, durable navigation device that floats and tracks waypoints, the GPSMAP 79s is better - especially for kayak anglers or as a backup nav tool. The price difference is significant: $65 for the Fishfinder (used) versus $309.99 for the GPSMAP (new).
Comparison
| Feature | GARMIN Fishfinder Depth Finder 80 | Garmin GPSMAP 79s |
|---|---|---|
| Price | $65.00 | $309.99 |
| Condition | Used | New |
| Primary job | Sonar fishfinding and depth reading | Handheld GPS navigation with compass, altimeter, barometer |
| Sensors | Sonar | Built-in compass, altimeter, barometer |
| Best for | Anglers who want dedicated depth/sonar | Boaters who want a rugged, floating handheld GPS |
Where Each Product Wins
The Fishfinder 80 wins if you want a low-priced, dedicated sonar tool that focuses on depth and fish signals without extra navigation features. The GPSMAP 79s wins if you want a brand-new, rugged handheld that floats, stores thousands of waypoints, and includes a compass, altimeter, and barometer.
Product Notes
GARMIN Fishfinder Depth Finder 80
The GARMIN Fishfinder Depth Finder 80 is a no-frills sonar unit for anglers who want real-time depth and fish signals without hauling along a navigation device. It's built with sonar sensors and supports both decimal and imperial measurements, so you can read depth in whatever units you're comfortable with. The plastic housing is made for marine conditions, and the unit is listed as used-something to keep in mind when you inspect it. If you already have a smartphone or chartplotter for navigation, this dedicated fishfinder fills the gap for under-boat imaging without adding a multi-function device. What it doesn't offer is waypoint storage, a compass, or a floating handheld form factor. It's a purpose-built tool, not a multi-function device.
Garmin GPSMAP 79s
The Garmin GPSMAP 79s is a rugged, floating handheld that takes the worry out of dropping your nav device overboard. It packs a built-in compass, altimeter, and barometer, and it can remember up to 10,000 waypoints so you can mark spots and return later. The IPX7 water resistance and sun-readable color display make it easy to use on a bright day, and the scratch-resistant glass adds peace of mind. It's sold as new, which is a plus if you want a reliable backup. The limitation is that it has no sonar or fishfinding ability-this is strictly a navigation tool. If you're an angler who needs to see fish, you'll still need a separate depth sounder. But if you want a handheld that floats and keeps you on course, this is the one.
Final Choice by Use Case
Choose the Fishfinder 80 if your boat already has navigation and you want a dedicated depth/sonar display. Choose the GPSMAP 79s if you need a portable, floating GPS with compass and altimeter for kayaking, small craft, or as a backup to your main chartplotter.
