With its large numbers and effective backlighting, the Raymarine ST40, our top choice, can be seen easily in daylight or at night.

If you don’t fish, why spend money on a fishfinder? If all you need is a number—the depth of the water—you might want to consider a digital depth sounder instead. They’re cheaper, smaller, easier to install, and a cinch to operate.

Diehard fishermen could find a digital sounder useful as well. For example, you’ve got your expensive fishfinder at the helm but no depth information up at the tower station. Solution: Install a digital depth sounder in the tower and link it to your fishfinder. Or if you want a backup to your fishfinder, install a digital depth sounder with its own transducer. …