Land & Water Mapping GPS Units

The below units are from Garmin - the world's best selling GPS manufacturer. They all feature:

Garmin GPSMAP 276C/376C/378/478 Chartplotter Family Feature Comparison
Features	GPSMAP 276C	GPSMAP 376C	GPSMAP 378	GPSMAP 478
GPSNOW Price	$599.99* Click [Add to Cart] to see our *MUCH lower unadvertised price!*	$899.99* Click [Add to Cart] to see our *MUCH lower unadvertised price!*	$999.99* Click [Add to Cart] to see our *MUCH lower unadvertised price!*	$999.99* Click [Add to Cart] to see our *MUCH lower unadvertised price!*
Automatic Street and Highway Routing with Turn-by-turn Voice Guidance?	YES - but requires optional auto navigation kit	YES - but requires optional auto navigation kit	YES - included	YES - included
Preloaded with City Navigator North America?	No	No	YES	YES
Preloaded inland lake maps (excluding the Great Lakes)?	No	No	YES	No
Built-in marine charts covering all U.S. coastal areas, including Alaska and Hawaii and the Great Lakes?	No	No	No	YES
XM WX Satellite Weather Capability*	No	YES**	YES***	YES***
XM Satellite Radio Capability*	No	YES**	YES***	YES***
Audible Weather Alarm*	No	YES - requires XM WX Satellite Weather**	YES - requires XM WX Satellite Weather***	YES - requires XM WX Satellite Weather***
Includes GXM 30 antenna?	No - Not compatible with GXM 30	YES	No Available by separate purchase	No Available by separate purchase
Includes 12-volt adapter with speaker for sound?	No - can be purchased separately	No - can be purchased separately	YES	YES
Compatible with Garmin BlueChart g2 data cards?	No	No	YES	YES
Complete Operating Instructions	Download	Download	Download	Download
Reviews (Independent and Customer)	Reviews	Reviews	Reviews	Reviews
	GPSMAP 276C	GPSMAP 376C	GPSMAP 378	GPSMAP 478
* An XM subscription is required (not included, requires separate purchase). Satellite weather and audio are only available within XM’s signal coverage area. ** For the GPSMAP 376C XM, sound requires optional 12-volt speaker cable (not included) or connection of headphones (not included) or wiring into the vehicle's stereo system from the unit's audio jack. An XM subscription is also required. *** For the GPSMAP 378/478 separate purchase of GXM 30 antenna is required. An XM subscription is also required.