Antalya aquarium is very good but does seem steep price. Was your quote including the Snow room? You shouldn’t need to do both.
There are plenty of shopping malls under cover.
Most hotels have indoor pools with free to use Sauna & Steam rooms and many have indoor games areas with Table Tennis/Pool Tables and Bowling Alleys - many have board games you can borrow
we’re in Belek at the moment and it’s Brightening up so are hoping to get outside today - still better than being back home