While looking for socks that do not show for European adventure travels, I purchased 3 different types. I have posted photos of them in different shoes in case it helps anyone. All are quite thin, great for the summer. I decided to keep the blue/grey ones (by Thirty48) for very open shoes and the 'Hippih' (lighter ones in photos) socks- I felt that those stayed hidden best in shoes, especially lower 'boat' type shoes (see photos with the grey shoes). The differences should be evident in the photos. All were pretty comfortable (though I do think the Hippih were a bit better as the others bunched a bit more in the back. All also have the thin silicone pads in the back that keeps the socks from slipping (no you cannot feel them, and I am pretty picky on foot stuff). On the photos, the pack of the rest of them is next to/above the foot wearing them.
All of them were great, I would give them all 5 stars, the two I kept simply worked best for my shoes.
Without further ado, the socks in the photos are:
 1. Thirty48 Women's Premium No Shoe Socks wiht Non Slip Grip (3or6 Pairs) [These are the blue/grey ones in the last photos]:
 https://www.amazon.com/gp/product/B01N101EJC/ref=oh_aui_detailpage_o03_s01?ie=UTF8&psc=1

 2. HIPPIH Women's 3-9 Pairs Casual Thin No Show Socks Non Slip Flat Boat Line [These are the lighter beige ones]: https://www.amazon.com/gp/product/B071DY7W2X/ref=oh_aui_detailpage_o03_s01?ie=UTF8&psc=1

 3. SPECIAL PRICE: Best Women's No-Show Non-Slip Socks for Casual Shoes - Sheec SoleHugger Active [These are the darker beige ones, usually on the left in most photos]: https://www.amazon.com/gp/product/B00B280WYS/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1