1. Canoe it.
Big Muddy Adventures (www.2muddy.com) offers various guided trips up and down the river, from three-hour daytime tours to full moon floats with dinners prepared by top chefs, such as Josh Galliano of Companion Bakery, on an island in the middle of the water.
2. Bike it.
Pedal along the Mississippi River Greenway (greatriversgreenway.org/greenway/mississippi-greenway-chouteau-old-chain-of-rocks-bridge/) from Chouteau to the old Chain of Rocks Bridge. The 12.5-mile trail built by Great Rivers Greenway will take you along the river's edge on both sides of the flood wall.
3. Stroll along it.
Take the grass-covered land bridge across I-44 to the revamped home of the Gateway Arch (www.gatewayarch.com). Learn your history at the newly renovated museum, which opens this summer. Lounge on the wide lawn or go down to the water and book a riverboat cruise on the Becky Thatcher or Tom Sawyer.
4. Photograph it.
Capture some birds from Bellerive Park (5570 South Broadway) or the adjacent Sister Marie Charles Park (199 Elwood Street). Eagles have been known to hang out in the trees here (especially around sunrise and sunset) and there's almost always a bunch of gulls diving between the barges. Bellerive also hosts a summer concert series.
5. Fish it.
Local anglers catch some massive catfish at North Riverfront Park (9400 Riverview Drive) and a few prehistoric-looking sturgeon. The diehards will fish this spot even when it's flooded and they're casting lines into the submerged parking lot. Further to the north, the Columbia Bottom Conservation Area (www.visitmo.com/things-to-do/columbia-bottom-conservation-area) is a great option, too, and it has a boat launch.