If you're shopping for marine electronics sonar navigation, the decision often comes down to a simple question: do you need to see what's under the boat, or do you need to know where the boat is going? Two Garmin units sit on opposite sides of that question. The GARMIN Fishfinder Depth Finder 80 is a dedicated fishfinder. The Garmin GPSMAP 478 is a GPS navigator chartplotter. They handle different jobs, so the right pick comes down to how you plan to use it. For many boaters, this is really a choice between a fishing tool and a navigation tool: the fishfinder helps you find fish, while the GPSMAP helps you find your way.
Quick verdict
Choose the GARMIN Fishfinder 80 if your priority is finding fish and reading bottom depth. Choose the Garmin GPSMAP 478 if your priority is navigation, chartplotting, and moving between marine and land GPS tasks. The deciding factor is whether you need to know what's below the boat or where the boat is headed.
At a glance
| Product | Price | Condition | Best for | Key details |
|---|---|---|---|---|
| GARMIN Fishfinder Depth Finder 80 | $65.00 | Used | Depth reading and fishfinding | Sonar sensors; Decimal & Imperial measurement; plastic; US |
| Garmin GPSMAP 478 | $99.90 | Used | Marine and land GPS navigation, chartplotting | GPS navigator/chartplotter; Manufacturer Part Number 478; Taiwan |
Where each product wins
- The GARMIN Fishfinder 80 wins for anglers who want depth and fishfinding data. Its dedicated fishfinding role and measurement flexibility make it the more direct tool for reading what's below the boat.
- The Garmin GPSMAP 478 wins for boaters who need GPS navigation and chartplotting. It goes beyond depth reading and can serve both marine and land navigation.
Product notes
GARMIN Fishfinder Depth Finder 80
The GARMIN Fishfinder Depth Finder 80 is the fishing-focused choice in this pairing. Its sonar sensors help you see depth and structure below the boat, and the Decimal & Imperial measurement system allows you to read data in either unit format. The plastic construction suits a life on the water, and the unit's origin is the United States. This is a depth finder and fishfinder, not a chartplotter, so route planning and on-screen maps fall outside its job. If you're an angler who wants to focus on what's under the hull rather than where the boat is heading, this is the more direct tool.
Garmin GPSMAP 478
The Garmin GPSMAP 478 is a marine and land GPS navigator chartplotter, so its strength is knowing where you are and where you're going. With the Manufacturer Part Number 478, this unit stands apart from the Fishfinder 80. It's positioned as a navigator/chartplotter rather than a fishing depth finder, and the Fishfinder 80 is the one with the dedicated depth-reading role. The practical move is to match the unit to your primary activity. If chartplotting and GPS positioning are what you need, this model addresses that job directly; if you're looking for a dedicated fishfinder, the other unit is the one designed for that task.
Final choice by use case
For an angler fishing over structure and reading depth, the GARMIN Fishfinder Depth Finder 80 at $65.00 is the better match. For a boater navigating unfamiliar waterways or moving between marine and land GPS duties, the Garmin GPSMAP 478 at $99.90 is the better match. The $34.90 price gap buys the chartplotter capability the fishfinder doesn't offer. If your day on the water is about finding fish, the fishfinder costs less and covers that job; if your day is about getting somewhere, the GPSMAP is the one to choose.
