In 1673, Jacques Marquette and Louis Jolliet passed a rock in the middle of the Mississippi River. Their Native guides warned them that the rock housed a "manitou," a demon that would devour travelers.

 Photographs never quite capture life on the river.

Photographs never quite capture life on the river.

The rock is a rare sight: a sliver of a former mountain, 400 million years old, the surrounding eroded, jutting up above the water. It's been a landmark for thousands of years, and feared for good reason. The narrow channel behind the rock has fierce rapids, which can easily overpower an unwary boat.

For us, though, Tower Rock was a beacon: our shelter from the storm. It was an early start for me, rising at 4:30 to pack my tent before the rain. Which meant that when it arrived, with a literal bang, I was in the open. I hunkered over the campfire while thunder and lightning raged. Fortunately, the lightning never came too close, and my rain gear functioned properly. We set out early amid a break in the rain, though it continued on and off all day.

So when we landed at an RV park across from Tower Rock for lunch, we decided to hunker down and dry out. Electricity, hot water, and sunshine: a fine triumvirate. The park is named Devil's Backbone, for another outcropping jutting into the river here on the Illinois side. You can see why the legends here are dark: these are sharp piles of rocks and jagged lines, caves tucked away above the water: strange and stark and spooky -- and beautiful. So unlike anything on the Lower river I know.