This mixed-species ape exhibit is outstanding for visitors, even though the habitat itself is not as natural-looking as many others. In the photo below the soft, bouncy floor can be seen, and a fraction of the absolutely enormous viewing windows. The shaded viewing zone is wide and filled with benches and so it is quite easy for a congregation of visitors to relax from the San Diego heat and watch the antics of the siamangs and orangutans.
On my 4 full days at the zoo during the past 6 years I've seen interaction many times between the species. The 110-foot long viewing window allows for visitors to stand next to the glass and get close-up opportunities with the apes, and the feeling seems to be mutual as it is common for the siamangs and orangutans to stay beneath the shade next to the 12-foot high windows. I've seen the species touch each other on the arms, and particuarly in the case of a young siamang a couple of years ago who was extremely energetic. I only wish that I lived closer to San Diego, but it is a 24-hour drive to get there and so even one visit takes 48 hours roundtrip of driving.