Maine experienced a “king tide” on October 9 that lifted boats and docks at the waterfront well above normal levels. King tides are the highest tides of the year and occur when the sun and moon align with the earth and exert combined gravitational pull on the oceans. King tides are normal but scientists are concerned about the intersection of these cyclical swells with climate-related rising sea levels and more frequent and severe storms. Maine representatives of an international collaboration of marine research and educational institutions are documenting king tides in the Gulf of Maine to help communities envision and prepare for the impacts of sea-level rise. Learn more and see other photos of October’s king tide .