Yes. Right before the underwater viewing comes into view, there is a secondary path that goes off to the left and uphill a bit, which leads to a small above-water viewing area on the left edge of the enclosure. I'm not sure if it was added at the same time as the rest of the exhibit, but its at least been there for the last couple of years.
@GraysonDP : I don't know the exact number, but I estimate it's probably around 3000 sq ft. I know that it is very similar in size to Cincinnati Zoo's new hippo exhibit.
I'm not sure impressive is a word I would use to describe it, although I'm sure the filtration system they had to install to keep the water somewhat clean is worthy of the word
I believe this exhibit (built at the end of the 1990's) was modeled after the hippo exhibit built at Toledo Zoo in 1986, as several hippo exhibits today are. The underwater viewing is very cool, and it is a treat to get so close to the animals. Ideally I would like to see a larger enclosure for such large animals, but they seem to do just fine: Saint Louis has 4 of them and they are usually either actively swimming or lounging in their pool. Overall, I would say that it is a decent exhibit and was worth the investment.