We saw some mixed reviews of the zoo, and that made us nervous. However, this zoo was amazing. We did the River Adventure and the Zoo parks in one day. It was a lot of walking (~6 miles) as we didn't opt for the free tram. The park is amazing. Animals are everywhere and not always contained, so stay on guard. They also have local troops of primates that roam the park that is not cared for by the staff, and they often get into other enclosures and steal food from other animals. The grounds are immaculate, like all of Singapore, and the staff is very knowledgeable. We went on a Thursday and it wasn't too crowded. I recommend getting a cab to/from, we used Grab to do that. Cellular was fine in the park for U.S. Verizon customers and they had free Wifi as well. Grounds also have lots of cover in case a rain shower moves through that allowing you to continue to enjoy the park. I highly recommend visiting the zoo.