Sleeping aboard a sailboat on a calm summer night can be one of life’s simple pleasures. For me, that typically means setting out two hooks in a V-configuration, just to have that extra sense of security, and arranging sheets and halyards to minimize noise in the rigging. I flip on the masthead light and settle in, feeling the residual roll and heave you can expect when speedboats have been out on the lake all day. After an hour or so, these swells flatten out, and slumber is deep and satisfying. Until, that is, there’s a major bump in the night, and you bolt out of bed to see what’s going on.

That’s what happened last summer around Labor Day. Debbie and I were boat-camping along the west shore of Lake Tahoe when, at about 2 a.m., I felt a dramatic rise and then fall of the boat. About 8-10 seconds later, there was another. When you’re sleeping, this change really grabs your attention, because you have the sudden and somewhat unpleasant sensation of falling.

I rolled out of the aft berth and climbed up on deck. In the moonlight, I could see a set of widely spaced, two-foot swells coming our way out of the northeast. The distance between the crests seemed like about 20 or 30 yards. In my fogginess, I was wracking my brain to think what would cause these swells on this calm and windless night. I began to think that maybe there had been a localized earthquake that caused them, but a quick check of my mobile news feed shed no light on that theory.

After discussing the phenomenon with a very sleepy Debbie, I decided to bundle up with a blanket and sit on the lazarette for a while to watch and see if anything changed. For more than an hour, this line of swells kept coming, never varying in wave height or wavelength. Staring out across the water, I eventually relaxed a bit and decided to go back to bed, visions of tsunamis put to rest. But I was still curious, so the next day I did some research and discovered seiches, or standing waves peculiar to bounded bodies of water like Lake Tahoe.

I knew from listening to the news earlier that day that there were high winds predicted out over the Black Rock Desert – about 100 miles north of Lake Tahoe – as the Burning Man Festival was happening, and burners were advised to shelter from the blowing dust on the playa. Lake Tahoe is pretty big – about 22 miles long – but evidently the low pressure acted on the northeast end of Lake Tahoe and set up the standing wave known as a seiche. Here’s a beautiful video posted by The Dam Café of Tahoe City that captures the essence of Lake Tahoe’s seiches. Just knowing that the seiche phenomenon is a “thing” will help me rest a little easier.

Fair winds and smooth sailing! DB