We know you love them. They're comfortable, easy to slip on and wash off, affordable, and they protect your toes (well sort of). And they have an arch which you know is good for you.
But I would never recommend Crocs for a long walk or for everyday wear. If you're headed for the beach or the pool they're fine, but that's it. Unfortunately many people wear Crocs all summer as if they're a perfectly good shoe or sandal, but they aren't.
Crocs don't secure the heel - like flip flops crocs won't keep your heel in place; when that happens you're going to grip with your toes which can lead to tendinitis, worsening of existing foot problems, and nails issues.
Crocs are not supportive - crocs are made out of resin which is very bendable. It's fine if you have a shoe that only bends at the toe, but shoes like crocs that can easily bend in the middle and can easily be twisted are not a supportive or stable shoe. Heel pain and arch pain can result from long term wear of unsupportive shoes even if they do have an arch.
Crocs can cause other problems - crocs can give people a false sense of security because they cover the toes. But because crocs have holes and the resin can easily be punctured, never wear crocs when doing any kind of yardwork or using heavy machinery. Crocs can also cause major blisters.
If you're after a sandal that can get wet and keep you out of pain I recommend that you buy Keens or Tevas available at REI or other sports stores. Both sandals totally secure your foot and have arch support to boot.