The indoor space for elephants at Wildlands is one of the best I've ever seen and I was there with a Dutch zoo enthusiast (
@jwer ) who also is a big fan of the habitat. Certainly
@Yassa has a good point that "there is way too much water", but if you look at the three photos of the indoor area that I posted on this thread then you can see that there is still a significant amount of usable land. The weird rocky areas are utilized by elephants and the rock-work is already worn from the heavy walking of the animals. This photo shows a sandy area for elephants that is almost certainly larger than 90% of all the indoor elephant enclosures anywhere in the world...and that's just a portion of the indoor area at Emmen. Take a look:
It's not perfect by any means, but Emmen's elephant accommodation is superior to just about every other zoo with elephants anywhere.
Even the outdoor zone is so much better than many small and sterile elephant exhibits that I saw last summer in Europe.
I've visited hundreds of zoos in North America and last summer I went on my first big European zoo trip. Here is an accumulation of the elephant facilities that I saw, although as you can see Emmen did not crack my personal Top 3 elephant exhibits...although it was close!

I'd probably place Emmen in the #4 position.
The zoos are listed in the order that I visited them.
19 zoos with Asian Elephants:
Artis Royal Zoo (Amsterdam, NL),
Diergaarde Blijdorp (Rotterdam, NL),
Zoo Maubeuge (Maubeuge, FR),
Zoo Antwerp (Antwerp, BE),
Planckendael Zoo (Mechelen, BE),
Pairi Daiza (Brugelette, BE),
Cologne Zoo (Cologne, DE),
Krefeld Zoo (Krefeld, DE),
Dierenrijk (Animal Kingdom) (Nuenen, NL),
Burgers' Zoo (Arnhem, NL),
Tierpark Hagenbeck (Hamburg, DE),
Berlin Zoo (Berlin, DE),
Berlin Tierpark (Berlin, DE),
Erlebnis Zoo Hannover (Hannover, DE),
Tierpark Strohen (Wagenfeld, DE),
Osnabruck Zoo (Osnabruck, DE),
Allwetterzoo Munster (Munster, DE),
Wildlands Adventure Zoo Emmen (Emmen, NL) and
Dierenpark Amersfoort (Amersfoort, NL).
3 best Asian Elephant exhibits:
Cologne Zoo (Cologne, DE) is easily #1,
Planckendael Zoo (Mechelen, BE) is second and
Diergaarde Blijdorp (Rotterdam, NL) third. There are, unfortunately, a number of fairly small, disappointing Asian Elephant exhibits that I saw on my trip.
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10 zoos with African Elephants:
Pakawi Park (Olmen, BE),
Pairi Daiza (Brugelette, BE),
Safari Parc Monde Sauvage (Aywaille, BE),
Opel Zoo (Kronberg, DE),
Wuppertal Zoo (Wuppertal, DE),
Duisburg Zoo (Duisburg, DE),
Safaripark Beekse Bergen (Hilvarenbeek, NL),
Ouwehands Dierenpark (Rhenen, NL),
Berlin Tierpark (Berlin, DE) and
Serengeti-Park (Hodenhagen, DE).
3 best African Elephant exhibits:
Opel Zoo (Kronberg, DE) is #1,
Safaripark Beekse Bergen (Hilvarenbeek, NL) is #2 with a troop of Hamadryas Baboons in with the elephant herd, and
Pairi Daiza (Brugelette, BE) third.