We took our then 1-2 year old grand niece on the "Oasis" and the "Harmony" (4 -5 years ago) and if I recall correctly they have a "Splash Zone" play area designated for toddlers and she was allowed in there with her "Swimmers" on.
I know for us (Young couple in our early 50's 😀) we prefer to use "Allianz". They offer way more options. We travel a fair amount so we actually purchase an "All inclusive Plan" for an entire year.