The adult pools were open until 10pm. Family pools were open until 6 or 7pm, I believe, Aquaduck maybe until 8pm.
It's quite possibly my biggest pet peeve with
DCL...as well as other cruise lines, all WDW resorts, and every other resort and hotel anywhere. Pools/hot tubs should generally be open 24/7, closing only briefly for cleaning and maintenance. The unfortunate result of an over-litigious society, I guess.