What is the importance of Niagara Falls in the novel, Take Me With You?

Seth and Henry want to surprise August by taking him to Niagara Falls. On their first summer trip they spread some of Philip's ashes at Yellowstone National Park and they talked about whether or not Philip was a risk taker who would have gone over Niagara Falls in a barrel if he could have been assured that he wouldn't have died. They come to the conclusion that he probably would have done it so Seth and Henry take August there and they put some of Philip's ashes in a little barrel and send it over the falls. It was a very sentimental moment for August because it meant that Philip was remembered by the boys eight years after they first learned who Philip was.