Calving glaciers make sounds...both above, and below, water/NPS screengrab

What sort of sounds do glaciers make, under water? Check out this video made at Wrangell-St. Elias National Park in Alaska.

We often look upon tidewater glaciers in awe because of their seemingly serene nature, but what is it like under the water? During a recent study in Icy Bay, along Wrangell-St. Elias National Park & Preserve's coastline, researchers deployed hydrophones (underwater recording devices) midway in the water column. They found that Icy Bay is really noisy!

Noise from glacier ice in Icy Bay is louder than most sounds found in the ocean, even louder than man-made sources like ship traffic and sonar devices. Much of this noise is generated from popping air bubbles as the ice melts in the salty ocean water. Some marine mammals, like harbor seals, may benefit from this noisy environment, and could use the loud noises to "hide" from their predators. As many tidewater glaciers in Alaska are retreating back to land, this may result in a much quieter environment.