At some point, I decided that this humble blog's ongoing bridge project also applied to pedestrian bridges, and later concluded that floating bridges are also in scope, so here we are looking at the Eastbank Esplanade's floating pedestrian bridge. I apologize for only having one photo of it; I'm still not sure how this happened, but I've meant to go back and take more for months now, and I haven't gotten around to it, so I think we'll just go with the one photo, and you can google it if you want to see more.)
When the city created the current Esplanade in 2000-2001, they wanted to build something with connections at both ends; the previous trail began at the Hawthorne Bridge and dead-ended at the Burnside Bridge (without actually connecting to the bridge) which made it rather useless. I-5 runs right along the east riverbank and even hangs over the river for a bit north of the Burnside Bridge, so there was nowhere on shore to put a new trail. So the solution they came up with was a 1200' floating bridge running parallel to the riverbank, just offshore. The city parks page about the Esplanade claims this is still the longest floating bridge in the country. That may change in the future, if a similar proposal in Chicago gets greenlighted. The proposed RiverRide system would add floating bike paths along parts of the Chicago River, since buildings are built right up to the river's edge in many places, leaving nowhere to put an onshore pedestrian or bike path. We'll probably just let Chicago win that one, rather than starting a new arms race of ever-longer floating bridges. I'm not sure where you'd put a longer floating bridge, for one thing. I suppose you could add length to the existing bridge by adding some gratuitous zigzags, though I doubt anyone other than the Guinness world record folks would be impressed by that.