There are two different ways to make aquatic exhibits in Wildlife Park. One way is to make a sunken enclosure. Or, you could make a fenced aquatic enclosure.
A sunken aquatic enclosure, is taking the terrain editor, and lowering a good amount of terrain a good amount. Then, place a few water pumps in the exhibit, and wait for the water to fill the enclosure. Once done, place the animal house of you choice partly in and out of water, and do the same with feeding containers and WALA!
A fenced aquatic enclosure is simply taking a solid fence and making an exhibit. Then, you put in the water pumps and animal house and food containers. Though it can be tricky when raising the land to place the house and container. Of course, you can always do half fence and half lowered terrain.
Hope this helps. :wink: