Talk about an OBLIQUEREFERENCE! That "Place to go swim, informally" clue was a bit too indirect for me! THEY. And I used to actually go to the Y to swim when I was younger! Sheesh! Nice one.
Other than that, though, this super-sized, 16x15 puzzle is right up our alley here at H&FDTNYTCPFCA, as we are big fans of reference books. A good old paper dictionary sits on my desk both at work and at home, and an Atlas has always been one of my favorite picture books to peruse at leisure. Almanacs are good for finding fun facts, and here's a secret - I have sometimes used a thesaurus while writing reviews! Why, just today I looked up synonyms for "oblique" and decided on "indirect."
The triple-checked squares often lead to some unusual fill, but aside from a little foreign material (ETATS, KRONER, ETUDES, TOILE, ROUE), and few oddities like MAE, SUEY, and ESTD, there wasn't too much that was SSS-worthy. Anyone else think that 1D should have referenced 2D in its clue? Hah! RIATA is kind of DATED, but I think most solvers have run into it enough by now to fill it in fairly easily. And that was a nice pairing at 19 and 20-Across, with "Ithaca, to Odysseus" (HOME) and "Odysseus, to Ithaca" (RULER).
I enjoyed the longer Down entries like GRAYSCALE (43D: It varies from black to white) (Perfect for this old-school photographer!), BARTENDED (42D: Made the rounds, say?) and WHATABORE (34D [Yawn!]) (Shades of yesterday's puzzle...). And I learned something new today with MACH (38D: Eponymous physicist Ernst). I definitely remember something better if it's been involved in a mistake I made, so hopefully, I'll know that one from now on!
A fun theme. I enjoyed it!