“I will tell you what you may not know from the videos.  He feels pain, he does bleed, but few attacks seem to penetrate deep enough past the surface to seriously harm him.  He is like the other two Endbringers in this respect.

So how do you defeat him? Just annoy him until he goes away?

Also Taylor has enough problems with doing damage to people like Lung or Hookwolf. What exactly does she expect to accomplish here?

“What sets him apart is his focus on water.  

Makes sense. A Leviathan is traditionally a sea monster, after all.

You’re likely aware of his afterimage, his water echo.  This is no mere splash of water.

I’m not entirely sure what this means but it doesn’t sound good.

At the speeds Leviathan can move, surface tension and compressibility make water harder than concrete.

So does that mean he runs around on the surface like some bugs do, but can’t slow down or he’ll sink?

He also has a crude hydrokinesis, the ability to manipulate water, and there will be water on the battlefield.  We believe that this is what lets him move as fast as he does when he is swimming.  Faster than he is normally, far faster than any speedster we have on record.”

Actually maybe we don’t want him to go under the surface.

I wonder if the storm is a result of him manipulating the water vapor in the sky. That said, it seems like it needs something more to go from clear day to maintaining a “buckets of water” rainstorm.