A man who is floating a junk boat on the Mississippi River hopes to make a point because this is literally a junk boat. 36-year-old Marcus Eriksen has been floating the length of the Mississippi River on a boat made up of more than 200 plastic soda bottles stuck in foam and held together by cast-off aluminum. Eriksen showed off his unique craft at the St. Louis Science Center Sunday. He said he is making the trip to point out how human use of the river affects its ecosystem. He and a free-lance journalist have been floating the river for two months and hope to make it to New Orleans by Christmas.