S.H.
new rule: if he won't take the shower afterwards, then there's no swimming.
Plain & simple.....he needs that shower to keep his skin healthy. At age 3, he is fully capable of understanding cause & effect. How about getting him interested in science projects at home....put lots of salt in some water, let him stick his fingers in it, & then let the skin air dry. Talk about the "tightness" of the skin, how it feels, & then translate that learning experience to swimming/showering! Never too early to learn....
As for a recommendation for lotion: any Aveeno product should be beneficial. I've been using it for years with the kids.