Hi Ben,
Welcome to the Disney Parks Moms Panel and thank you for sending us your question.
The Big Blue Pool at Disney's Art of Animation Resort is one of my favourite pools at Walt Disney World Resort, it is so much fun, and I love how we feel immersed in Finding Nemo.
Pool hours along with lifeguards on duty are always subject to change and are updated regularly at Walt Disney World Resort Hotels. After calling to verify hours, the Cast Member verified that current pool hours at The Big Blue Pool are 10:00 am until 9:00 pm, and after 9:00 the resort observes quiet hours. In my experience, the Big Blue Pool is gated and when the pool is closed, the pool has been locked for guest safety. The Flippin' Fins Pool and Cozy Cone Pool are not gated but do observe quiet hours as well. The hours may also vary from pool to pool.
Personally, I like to visit the Big Blue Pool during the late afternoon, to enjoy all of the pool activities and games. Because these games happen mid-day, the pool is not terribly crowded and we have so much fun!
I hope you have a wonderful time at Disney's Art of Animation Resort, Ben. Please let us know if you have any other questions, we are always happy to help.
Stephanie