Such an incredible story. In an article from Relay Hero, a chimp was in an aggressive altercation with another chimp. Suddenly, one of the chimps fell into the murky moat and was starting to drown. Against the zoo keepers warning, Rick Swope jumped in the water to rescue the drowning chimp. Swope recovered the chimp and managed to get him on the bank.
Although the footage was taken in 1990, you can see the natural instinct to save a drowning animal.