I found this interesting, and I have a related little back story: At least 2 seasons, if not 3 ago, I pulled into a little shallow divot close to the FS cabin in Pigot bay to clean fish and shrimp. It was dead calm...perfect day for a no-see-em to attempt a new speed record. All of a sudden, LOUD rumbling, freight trainy sound. It lasted close to 2 minutes, I'd guess. There was a boat directly across the bay from me, and when it started, they were instantly outa there and made the turn toward Whittier. I stayed put and nothing materialized. About an hour later, the other boat came back down the side I was on and stopped to ask "did you hear that?" They do their anchor thing with their pot puller same as I do with a buoy always tied to the bitter end. If the need arises, they can simply pitch the whole thing overboard and beat feet. That's what they did and were coming back to pick it up. I always wondered what happened and figure there was a landslide way up country towards Pigot glacier that thankfully didn't reach water. It was pretty weird!