I like this his kind of decision as a child who knows his limits and capacity, had it been that the child didn't insist on staying off the beach, it would have turned a miserable experience on him when he can't swim and find himself in the midst of the water, I've seen several occasions like this whereby children got drawn in water, the child may feels intimidated but he is not going to risk his life to please others, when he should rather pick up the challenge to also learn as he grows up.
I have worn that shoe in the past while in school, my friends dragged me to swim just like in similar scenerio, the pond was out of sketch in the city, I was swimming on the shallow part of the water and these people pushed me to the dip center, I was really scared and screamed louder until they changed their mind, and helped me out of the water. The boy was a good reminder of that experience and what he did unlike me was the best, because the vibe could change over time and he'll be tempted to jump into the water subconsciously. Then risk getting drowned in a lonely part of the county.