WOW!! I've only been here once or twice because it's so expensive but the price is totally worth it and you can tell the difference when compared to other zoos.
I'm originally from St. Louis where we have a free zoo so I was surprised when I moved to San Diego that the zoo was so pricey, but the difference is profound. The animals are so healthy and active whereas in St. Louis they hide most of the time or are sleeping. They feed the animals more naturally here by having them search for their food instead of giving them a bowl full. The enclosure quality is gorgeous as well as the entire park's landscaping. It's just an amazing place to be and definitely well worth paying the extra money for.
I do suggest getting there very early because dowtown San Diego is not fun to drive in (sudden change from three lanes to one lane!!). And try to find off-street parking (save the parking money for admission), Balboa Park is beautiful to walk in anyway so you might want to walk anyway.
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