I buy these TYR thermal suits every year for my kids from the time they are toddlers.  They are wonderful for days at the pool or the beach when the water is not quite warm enough.  Nothing stops my little ones from going in the water and it's hard to get them out, even when their teeth are chattering from the cold.  These suits really keep them warm and provide some nice sun protection too.  An extra added feature that we enjoy is that the suits keep the sand from collecting everywhere :)  An investment well worth every penny and they last from year to year so we always pass ours down to friends as the kids outgrow them.  This pattern made my 6 year old VERY happy.