Bays and harbors naturally resonate with standing waves, known as seiches. Seiches are usually considered temporary, however, we identify small-amplitude, continuously present seiches in six bays around the Pacific and suggest that tidally forced, continental shelf resonances are a primary driver of continuous seiches.

Changes in mass transport of the Florida Current induce significant coastal sea level changes along the Florida Straits and middle Atlantic coast of North America. Analysis of Florida Current transport data finds a decrease in mean transport over the last decade. This decrease coincides with a decrease in AMOC and acceleration of coastal sea levels along the Florida Straits.

Seiches in coastal bays can produce significant water level oscillations that impact maritime operations and introduce ecological stress. Monterey Bay, California, is found to have wave-driven short-period oscillations that can reinforce themselves, resulting in water level amplification. At longer periods the oscillations are not wave-driven and several potential forcing mechanisms are examined. A gyre offshore the bay is suggested as the driver, while other potential drivers are discounted.