And yes, it's wise to get some cheap "water shoes" for beaches. Many beaches are lovely golden sand, but others, just as beautiful, are pebbly, at the verge, and wading in — that's why flip-flops won't work; you must shed them at waters edge, and the pebbles continue.
How do you use the bathroom in Greece?
Public restrooms in Greece cost money (around 50 cents).Most restrooms are fairly clean, but many of the toilets don't have seats so you'll need to squat over them. To be safe, I recommend carrying around some hand sanitizer in case the bathroom you visit doesn't have soap!