What are the hours of operation for the Royal Babies and Tots nursery?
Because Mariner has just started sailing again after her extensive refurbishment, I have not seen a cruise compass yet that lists the hours of the nursery on board. That being said from my experience on other ships, it will either be open from 9am-12pm and then again from 2pm-Midnight or from 9am all the way until midnight on sea days. On port days the hours may change depending on when you are in port.
When you get onboard the ship on the first day their will be a Royal Babies and Tots Nursery Cruise Compass that will list the nursery hours for your entire cruise, unfortunately until you see that anything I can tell you is never set in stone. Hope this helps some and sorry I can't be more help.