Protect her feet wherever she paddles. Family adventures across the water sometimes reach rocky shores or gravelly riverbeds. You can worry less about her feet getting scraped when she wants to jump in the water. If it's cold out, neoprene shoes can ensure her toes stay toasty.
A good pair of water shoes drain and ventilate well to dry quickly. Too much water weighs the shoe down and makes movement difficult. They should fit snugly but remain flexible enough for her feet to shift around without causing rubbing.