@KaiGoesMandai I'm guessing this might have been a Capybara enclosure previously. The bit on the left side of the photo is a pool (but empty). I think the holes might have been for visitors to feed the Capybara through, if that was the case.
@Chlidonias that is unfortunately not the case. The tropical wetland section was opened in 2016 with lowland tapirs in that narrow exhibit along with tapir feedings through the holes. The capybaras were in the first part of the Tropical Forest area with the bush dogs and other tapir enclosures back when that area was called “Aqua Valley”.