Swimming aids

Hi All

I am looking for a swimming aid for our son, he is just over 2yrs old and loves being in the pool however he doesn't like to be held and wants to be in the big pool. He had a swim ring with a seat which was perfect but he has now outgrown it, can anyone recommend anything that we can use that is safe.

I have looked for the next size up in swim rings with a seat but he has the biggest they make.

Thanks