While stationed in Duluth, there was a riptide related death on the lake side of Minnesota Point. It was August 17th, 2003. The lake was abnormally warm, partially due to the strong onshore winds holding the warmer water against the beach. So there was a lot swimmers out in the high waves. This unfortunately created a dangerous rip current situation, and a 21 year old died because of it. Junior Lessard, future Hobey Baker award winner, was also caught in the current. He was rescued by a surfer.
I was on the bay side of the point that day kayaking. I didn’t want anything to do with those big waves, and the bay had calm waters. I saw the helicopter hovering over the beach from afar, but didn’t connect that it had anything to do with riptides. I thought it was a boat related incident.
Two or three weeks later I snapped a few beach pictures in an attempt to help me understand riptides. No big winds that day, so the pictures aren’t particularly dramatic. This first picture shows the character of the beach. It isn’t straight. There are parts that stick out into the lake (I call them ridges) and the in-between areas that I call troughs.
The lake is shallower over the ridges compared to the troughs. So the waves shoal sooner when going over a ridge (example below).
So the water that flows over the ridge, drains into the adjacent troughs, and flows out back into the lake. This flow is the rip current. Each wave that comes in refills the trough to fuel the current. If you are caught in this current, you will be swept out into the lake with it. Now that you understand this, it makes perfect sense to swim sideways (parallel to the beach) when caught in a current. You swim sideways until you are even with a ridge, away from a trough… then you swim toward shore. The NWS published a page to better explain this.