The African Elephant exhibit was completed in 2005 and the pool is definitely enormous. The zoo has been maintaining 3-4 elephants at one time and while the land area is not large I'm not sure that I've ever seen such a huge amount of water for pachyderms.
The penguins have since been removed; until a more suitable exhibit can be built for them, but I never saw any intra-specific interactions. The elephants ignored the penguins and the penguins pretty much stayed in the plantings around the outer edge of the pool. Although they would occasionally hang out on the bank of the elephant yard.
