Whenever I see this picture I think of this:
| Creature | Swims | Walks | Flies |
| -------- | ----- | ----- | ----- |
| Dog | X | X | |
| Fish | X | | |
| Bird | | X | X |
| Duck | X | X | X |
Notice how for each combination of swimming, walking and flying, there is a living creature that can do just that, with the exception of swimming and flying.
Sure there are flying fish, but they glide rather than fly. Did evolution really forget to cover this niche?
I would vote for the gannet as able to fly and swim. They dive incredibly fast to catch fish, so they go deep, and once down there, they use their wings to swim after fish.
Great article here, with photos: https://www.naturettl.com/underwater-world-gannets/
So while it needs to get out to breathe, it can still swim underwater for as long as it has breath. Nice.
However, those feet look like they can be used to walk.