In northern Nova Scotia, where the Shubenacadie River meets the Bay of Fundy, the world's gnarliest tides – a record 53-foot range was once measured here – barrel into this little river. The result is a wave-and-whitewater cauldron that draws people in boats to ride the tide. At the Tidal Bore Rafting Park, seven hours from Bangor, Maine, guides take tourists on 16-foot Zodiacs with motors, head downstream, and then turn to face the mouth of the river. Once you can see the white line of foam barreling down, you have a few minutes to brace yourself for a half-hour of Zodiac boogie boarding in five- to seven-foot waves. Then the 10- to 15-foot waves start pouring in, bringing on more chaotic whitewater. The big waves slam against the boats for an hour before the calm settles back in and the boats return home, at least until the next high tide. [raftingcanada.ca