In case anyone was still wondering, I may have found an answer to this. I add the qualifiers because I'm getting it second-hand from another forum, due to not having reached the Stormblood areas yet, but I think it's plausible enough.
Basically, the answer is no, the Elbst mount cannot swim. However, there is apparently an actual lore reason for this: the Elbst mount has had its flippers clipped to allow it to run on land. No word on whether this contravenes animal cruelty guidelines.
I wonder if this forum has a way to reply to a thread without bumping, for minor additional-information posts like this.
Basically, the answer is no, the Elbst mount cannot swim. However, there is apparently an actual lore reason for this: the Elbst mount has had its flippers clipped to allow it to run on land. No word on whether this contravenes animal cruelty guidelines.
I wonder if this forum has a way to reply to a thread without bumping, for minor additional-information posts like this.