I came back to post ‘Free Ride’ damnit.
Rock the Boat hasn’t been posted yet, so i’ll do so.
Hot Summer Day - It’s a Beautiful Day
Thunder Island
And pretty much everything that comes up on that page 
This was the first one that came to mind for me. Anytime I hear it, it instantly brings me back to our neighborhood pool in the late 70s/early 80s.
“All Right Now” by Free and “Maggie May” by Rod Stewart.
Elton John’s Island Girl and/or Captain Fantastic and the Brown Dirt Cowboy
Michael Murphy’s Wildfire
Ma Cherie Amour by Stevie Wonder.
I’d call that one too romantically intimate for poolside. Also has a sorta introspective feel that would really count it out.
I’d opt for his “Boogie On Reggae Woman” or “Masterblaster”.
I included this one out of actual memory. I was lifeguarding at a pool one summer in the early 70s and this song played on local radio at least once an hour. I always think of it whenever I think of the Elk’s Club pool and my lifeguarding gig.
But yes, the others you suggest fit in more with the theme you are going for.
Games People Play, by The Spinners
The first song I thought of was “Sunny Days” by Lighthouse.
“The Boys in the Bright White Sports Car” by Trooper is a good summer tune, too.
I seriously doubt anyone heard this song at a local swimming hole in the 70s, but I think Earschplittenloudenboomer is a perfect tune for lazin’ round the pool.
Agree with Anamorphic and FoisGras that “Baker Street” is the perfect choice, and with kiz that anything by KC and the Sunshine Band is just right as well.
And anything by Sly and the Family Stone (blondebear mentioned one), but they were “hot and happening” just a couple years before my time. (I grew up with them indirectly, via their influence on the sonic atmosphere of Sesame Street).
How could we not have Springsteen’s* Born to Run* and Spirit in the Night?
I remember the 70’s pool I went to as a kid played The Eagles “Heartache Tonight” and Fleetwood Mac “Don’t stop” pretty much all summer.
Diana Ross: “Ain’t No Mountain High Enough”
Linda Ronstadt: “You’re No Good”
Carole King: “I Feel the Earth Move”
Cher: “Gypsies, Tramps, and Thieves”
Carly Simon “You’re So Vain”
Peaches & Herb: “Reunited”
Stevie Wonder: “You Are the Sunshine of My Life”
Chuck Mangione: “Feels So Good”
Joe Walsh: “Rocky Mountain Way”
Jackson Browne: “Running on Empty”
Yes: “Roundabout” The album version, not that silly single edit.
Eagles: “Best of My Love”
Doobie Brothers: “Black Water”
Wings: “Band on the Run”
Stories: “Brother Louie”
Steve Miller Band: “Fly Like an Eagle”
Partridge Family: “I Think I Love You” (Don’t laugh, it’s objectively a well-crafted pop song, as such things go)
Dawn: “Knock Three Times”
Three Dog Night: “Joy to the World”
Rod Stewart: “Maggie May”
Johnny Nash: “I Can See Clearly Now”
Neil Young: “Heart of Gold” and “Like a Hurricane.”
(Actually, I just came here to post “Feels So Good” and “Like a Hurricane”; the rest are filler—but good filler.)
Thunder Island! ::makes note to add to 70s mix on iPod
Guardians of the Galaxy 2 reminded me of the existence of Glen Campbell’s “Southern Nights”, another good one.
Quirky: Loudon Wainwright III Swimming Song
This summer I swam in a public place
And a reservoir, to boot,
At the latter I was informal,
At the former I wore my suit, I wore my swimming suit.
Me too with the Lighthouse. The second one ain’t bad - with me, it was literally Trooper’s “Santa Maria”* - associating it with a buncha (ancient, lost-in-Sir-Ian-McKellan-land) summer memories, trekking out to the Gulf Islands.
*Great - I’m now actually commenting unironically on Trooper.
Maybe should “just step away from the keyboard” for a spell.
How about something by Spirit?
I don’t see Badfinger on the list–how about “No Matter What”?
Amazing. I hope that wasn’t the line-up that actually went on the road, or else I could easily envision a whole lot of squabbling over divvying up the gig money. I liked the seated hirsute guitarist who still managed to rock about as hard as any other guitarist could on a stool. Mr. Fripp would be humbled.
Great tune, though.