Oh, I can guarantee you they are both in Wildlife Park 2the Bottle-Nosed Dolphin and Orca is NOT in Wildlife Park 2 (but other dolphins)
All the Wildlife Park 2 fully aquatic base game animals are:
- Anglerfish
- Basilosaurus
- Bottlenose Dolphin
- Giant Squid
- Great Hammerhead Shark
- Great White Shark
- Manta Ray
- Octopus
- Orca

Anyways, but now back to Planet Zoo

What I hope for is pretty much a habitat system like the Zoo Tycoon 2 option.
In my opinion PZ already pretty much has the basics for that already. We can already pretty much built such tank like features. Its just missing an access for the keepers and the ability to add the animals directly into the water. But I have faith the Devs could make this possible.
Other than that we already have the underwater feeders, underwater enrichment and the "normal" enrichment items can float already anyways, we have the water filtration and heater machines already, we can change the water colour and there are some water effects we can choose already.
So I would say we only need, as already said above, a keeper access for such a tank. Also it would be great if they added salt water to the game. There are even 2 options how they could do this:
- A new salinity machine (like the filitration and heater)
- An option to choose similar to the way water colour works
Animal wise I am of course thinking about the "big boys" for those habitats, my 8 animal wishlist would be:
- Orca
- Bottlenose Dolphin
- Beluga
- Amazon River Dolphin
- Harbor Porpoise
- Pacific White-Sided Dolphin
- West Indian Manatee
- Dougong

Small fish should simply be in exhibits^^
And for medium to bigger fish (as well as sharks) I imagine a walktrough-underwater-tunnel-exhibit for them were the guests would walk through a tunnel to see the animals from underwater (well, obviously..). Also a kind of "pond-walktrough" would be nice, were the guests simply walk over a bridge over a pond, were we could house fish such as kois, goldfish etc.
Other than that I also though about the "JWE2 Lagoon Method"
This would of course also only work for the big animals, though, but I dont think that would be a problem, because in my head the fish and such already are exhibit animals, anyways

Now the lagoon system wouldnt be perfect, like you dont really have alot of freedom how you bulit the habitat, but you have at least some how to place and expand the pools. For PZ Frontier might be able to improve the system. I would be fine with such a system as long as the animals in it count like "normal" habitat animals, you know, with offspring models, family tree, being moveable between zoos etc. But for the builders this could be really bothering, so it probaly wouldnt be ideal. It would be a good compromise though, should the habitat pool method not work.