That little spit of land is the confluence, the point where the Missouri (mid-ground) and Mississippi (foreground) Rivers meet. There is an awful lot of water passing through. You can drive almost to the junction and walk out to that tip unless the rivers are in flood.
The pictures were taken from the top level of the Confluence Tower in bad weather. It's the site of yesterday's picture with Ellie. The deck is 150 feet / 46 meters off the ground. Wish there had been more to see.