My advice and find some other vacation with your child.
Only Disney lets kids with diapers in a pool.
On the Disney Magic, the Mickey pool has a separate filtration system. Non-potty trained children are allowed in this area since it can be easily emptied, cleaned and filled if there is a diaper accident.
On the Disney Wonder, toddlers can enjoy Mickey’s Splash Zone, a 385-square-foot play area with interactive fountains.
NONE I hope, that’s unsanitary and disgusting.