If there's a surfable ripple anywhere on Earth, Ben Gravy will sniff it out. The latest stop on the novelty-wave specialist's never-ending quest took him to Canada's Petitcodiac River, where he chased the elusive phenomenon known as a tidal bore—a wave created when an incoming tide pushes upriver against the natural flow of water. The setup sounded promising. According to Gravy, the incoming tide surge measured roughly 20 feet, transforming the river as seawater rushed inland. The actual wave, however, was another story. Turns out, even 20-foot tides don’t make 20-foot waves. Rather than a roaring wall of water, the tidal bore resembled little more than a moving bump sliding up the river channel. For most surfers, it would hardly qualify as a wave at all. For Ben Gravy, it was perfect. Armed with one of his trademark oversized soft-top surfboards, Gravy paddled into the tiny surge and somehow found enough energy to glide along its face. As always, the wave itself wasn't really the point. The adventure was.…