Beautiful Earth on Instagram: "This sudden wave was caused by a tidal bore — a rare phenomenon where the incoming ocean tide rushes up a river, creating a powerful surge that moves against the flow.  It’s unpredictable, fast, and a reminder of how powerful nature can be. This can even be seen in places like Turnagain Arm, Alaska, one of the few spots in the U.S. where tidal bores occur.  #naturefacts #earthwonders #tidalbore #alaska"