Topic
Yes.
Swimming constitutes part of an exercise regime for many racehorses.
Link.
Remembering the books Stormy of Chincoteague and Misty of Chincoteague and smiling- nice childhood memory! (They and other ponies swam across the Assateague Channel every year)
Of course. How the hell do you think they play water polo?
On seahorses?
Horses swim fine even with a rider on top. I did it once across a crocodile infested river in Costa Rica. I mean that literally. The guide had us walking up and down the bank until we found a place where there were no visible crocs and it took a while.
Riding on a swimming horse is an odd sensation especially when there are crocodiles around. The guide and I made it across the river with our horses up a steep muddy bank on the other side. However, my wife is a lifelong expert rider and her horse tumbled backwards into the river throwing her into the river as it tried to leap up the embankment. Both my wife and her horse were visibly shaken but they ended up just fine but very wet and muddy.
Some horses despise water however and it is difficult to get them to look at it without getting spooked let alone swim.
My wife just asked me this when we saw Elizabeth.
I’ve seen pictures of Cossacks on horseback swimming through a lake in a traditional Russian festival. Can’t remember where I saw it but it was definitely a recent photo.
Elephants can too. :o I think all mammals can swim, no?
ETA: Humans excepted. I guess we think about it too much.
It’s also becoming the rehabilitation of choice for horses with damaged legs, Equine Swimming Pool, Equine Water Treadmill. Allowing the horse to work it’s muscles and increase blood-flow to to it’s legs without the risk of putting full weight on say a screwed together and repaired but otherwise still broken bone.
Morrisville College Foundation (MCF) Equine Rehabilitation & Physiology Center
CMC+fnord!
They can even dive.
I reckon you never watched a Western movie when the cowboys forded a river? Sometimes when the water is deep/swiftly moving, the rider will slip off and hang on to the tail … but yes, horses can swim.
Damn, that was funny. 
I seem to recall that giraffes can’t?
I know no one has ever reported seeing a giraffe swim but then no one has reported throwing one into a really deep lake either… 
Apes can’t swim. Which is why the humans pray for rain.
From same source:
Apes are the members of the Hominoidea superfamily of primates, which includes humans… 