Interior of house has small but deep pools to which hippos have practically 100% access but often choose to stay in the paddocks. In the summer a shelter is put up in the paddocks to shade from direct sunlight.
This photo was taken in August but as last summer was so wet, the shelter never appeared.
House & 2 paddocks now all for pygmy hippos. Until 2 years ago, left hand side held Malayan Tapir.
Interior split into 3 small enclosures (each with pool) with high level public viewing. Originally built in the 80s the building is known as the 'semi-aquatic mammal' house and for short time held hippo, tapir and capybara.
I think the animals just prefer a heated pool, and there's always the issue of the hippos not using them in Winter. They do a put a sunshade up in hot weather.
It's worth noting this enclosure has had a significant amount of landscaping done in recent years. I was surprised by the amount of logs and cover in it when I visited recently.