A Seiche Nearly Sweeps Divers
By Scott Seaborne
Our group of 10 student divers had traveled to the very tip of the peninsula of Door County, Wisconsin to complete the last of our open water dives for certification. The Door County peninsula is bordered on the east by Lake Michigan and on the west by long and narrow Green Bay.
That evening in our cabin we sat around the fireplace, reading historical accounts of the many ships that wrecked near these shores. A map in our shipwreck book showed a nearby spot that had claimed more than its share of ships. This spot was identified by the early French explorers who named it Porte des Morts-"Death's Door." When my wife, Betty, and I went to sleep that night, we could hear the wind blowing and the waves crashing against the base of the limestone cliffs below our cabin.
Bright shafts of sunlight streamed through our bedroom window as we rose the next morning. The storm had passed. We drove to the beach but found very high surf whipped by determined winds. We did no diving that day. The next day was much the same; clear and cool with a brisk northwestern wind.
One of our instructors suggested we try the leeside of the peninsula as we were running out of time to complete our open water dives. We collected our gear and drove through the maple and birch forest to the very tip of the peninsula. Soon we arrived at a stony pebbled beach between two limestone bluffs. The water was relatively calm. Betty and I donned our dive gear, with full one-quarter inch wetsuits, and waddled to the water's edge. I saw a small rock edged island about one-half mile from shore. I asked the instructor the name of the island and he replied, "That's Plum Island and the passage between is called Porte des Morts!""Historic!" I said as Betty and I swam out to the flags that had been set up for our underwater compass run.
When we reached the flags they hung limp. The wind had finally calmed and I was glad the weather would not be a distraction to our dive. We took a compass bearing on the other flag and descended to the bottom at 15 feet. When I turned to look at Betty, her gaze was solidly fixed to the compass on her wrist.After following our heading for some time, I became puzzled we had not seen the flag floatline and anchor. I rolled on my back to look at our instructor. He seemed perplexed, too. He motioned to surface.
On the surface, we discovered the flag was 30 feet to our left; perpendicular to our compass heading. Todd, our instructor, was baffled by the size of our error as he was using his compass, too. We decided to swim to the nearest flag and take another reading. We tried to surface swim toward the flag, but it soon became apparent we were not getting closer. We stopped and looked toward shore. Slowly, we came to realize we were drifting away from shore toward the open expanse of Lake Michigan. Calmly, but with a taut expression on his normally smiling face, Todd told us to "Swim for the beach now and don't stop!"
It was hard to know if we were making any progress. I knew if all else failed we could inflate our BCs and wait for help, but it was late afternoon. Darkness would soon be upon us and Lake Michigan is very cold. I continued to kick. Betty began to tug on my arm, complaining she was exhausted and having trouble breathing. Todd unzipped the front of her wetsuit and told me to help him tow her into shore.
Todd and I each took one of her hands and resumed kicking. I have no idea how long we kicked but it seemed like an eternity. Just as I thought my lungs would explode or my legs cramp, I felt a firm pulling on my BC as others in our group had waded out from the beach to drag us to shore. Betty and I collapsed, exhausted on the beach.
What had happened?
Here is what I learned from this experience. We had been victims of a seiche (pronounced saysh). The strong winds that had raked the peninsula for several days had literally bulldozed tons of water into Green Bay, raising the level at the far end. When the winds died, all the trapped water began to flow immediately back into Lake Michigan, creating a powerful current. Other lessons learned: ask the locals about unusual conditions before you dive an area you are unfamiliar with; stay in good physical shape; and, when faced with danger, don't panic.
- "Ask locals about unusual conditions before you dive an area you are unfamiliar with."
- "Stay in good physical shape."
- "When faced with danger, don't panic."