The Seine is literally the aqua artery of Paris and the scenery changes depending on where you are along the river. The Bibliotheque Francois Mitterand (National Library) is only two blocks from the Seine and if you are lucky enough to have a blue sky day, the waterfront is a much nicer place to read.
The sights include barges and tugboats which have been converted to cafes, clubs, and special event spaces.
Parisians live with beauty as a part of life. So having a snack on a barge
with a view like this is normal:)
It is still August, so the roads are eerily empty, even around the Gare de Lyon and
the view from the bike lanes underneath the roadway looks like a futuristic movie.
Yes you can swim in a pool ON the Seine! Piscine Josephine Baker is a converted barge which is completely handicap accessible and costs only 3 Euros ($5 US) to enter. They have classes and activities for all ages and levels, so if you want to come back on a regular basis you can buy a carnet of ten passes (like metro tickets) for a discount.
I prefer walking to swimming, and with the clouds looming, it looks like it's time to walk to the nearest metro station:)