It might be safe to say that trolling lures for blue ­marlin in the calm and tranquil waters off the Kona, Hawaii, coast is as good as it gets. With three towering ­volcanoes ­setting the backdrop, ...

The Swedish-made Probe device is designed to help anglers catch more fish. It does so by following their lure down into the inky depths, recording the depth and conditions at which the fish strike.