To navigate within the single photo view:

Swipe left, right, or up (to exit slideshow or close single picture)

To download photos:

On a computer, simply right click and save the photo. That’s it.

For mobile device, the process requires a few steps.

1) Long click on the individual photo from the gallery view, the page with multiple pictures.

2) Scroll down on the menu of the photo.

3) Click ‘Save to Photos’