@SivatheriumGuy I zoomed in on my photos to check. It looks like the barrier consisted of large wooden posts in the water with hotwiring on top, above the waterline.
So I guess the hippos didn't cross the poles because of their size? Seems like a clever way of keeping them. Do you have any idea of why they moved to their current exhibit? Which one do you consider to be the best?
@SivatheriumGuy Yes, the poles were close enough together than a hippo could not pass between, and probably also strong enough so they couldn't move them out of the way.
With regards to the comparison between this exhibit and the current one: I believe this one was actually larger (if only a little) and the land area was definitely larger.
The newer one has an underwater viewing area and relatively clear water, so visually the newer one has a little extra.