Near the end of the chapter, when arriving at the party, Max will talk to the coat check girl, then go through the curtain into the pool area. After a cut-scene, head to the right of where you entered (only a few steps away), around where a lifeguard stand/ladder thing is situated. The correct position isn't directly under the ladder, but maybe one or two steps past it as if you're doubling back toward the wall on that side. Look up at the windows and there should be a photo option of what you can see in the sky outside.