The Depthfinder / GPS Combo is the most popular form of marine electronics sold today.  Advances in technology have provided units with powerful sonars and fast, accurate gps receivers.  Larger screens with brilliant colors and vivid detail, easily viewable in direct sunlight, large memory capacities, and slots for removable memory cards and map chips are additional features that savvy anglers use to their advantage.  A wide variety of full-screen and split-screen modes allow users to fine-tune these units to their specific needs.