There is something strange about this lake.

I feel like I'm supposed to be noticing something obvious.

 

There's no Shiny Gyarados?

 

It's not even close to obvious. It's the kind of thing that you'll kick yourself for no noticing, though. Here's a version with a giant cat in the background.

 

I think I've got it.

Spoiler

It's not a lake. It's a wall.

 

Guys, it's so obvious.

That rock about a centimeter up from the bottom is obviously fake, whoever did this is a master of photoshop.

 

I think I get it. It's strange because the water looks like pee?

 

Yep, that's it.