We did that tour just two weeks ago. All of us (family of 4) had strap-on type sandals. I wore Keen, my boys had Stride Rite and my husband wore a pair he bought from the Walking Company years ago. All of our sandals were designed to go in and out of the water and they were perfect. There are a lot of slick and uneven spots. You can go from dry to wet in the blink of an eye, too. I was thankful for the sturdy and supportive shoes. I own Crocs but my feet always slide around in mine when they get wet. I don't know that they would be the best choice. It is a beautiful place. You will love it!