My SAD kit includes a small roll of vet bandage, which is waterproof and works well in place of lycra socks if you get a blister; could also be used to cover any other random abrasion.
Already posted, but I bring a small meds case with 6 or 7 basic meds. Also a Z-pack, which saved a trip to Argentina for my wife many years ago.
My wife's silicone mask strap broke on our last trip, which was a new one for me, so would recommend a spare strap or better yet, a spare mask that fits.
You're unlikely to need the vet bandage for a blister if you're using lycra socks. 20 years ago, my feet were always hamburger from my booties but lycra socks changed all that. The only time I've had hamburger foot since was the time I lost one sock. Hence, I have since traveled with 3 pairs. One pair of raggedy ancient socks that look like crap but still do the job for other divers experiencing hamburger feet because they hadn't yet learned of lycra socks, and two newer pairs for me, in case I lose/misplace a sock.
I hope to never lose or forget to pack my socks again.