Q: Just how do you navigate through these galleries?
But more precisely, click on the type of image you want to see (flowers, waterfalls, etc.). This will take you to the first page for that set of images. Once you are at a page with smaller "thumbnail" images, you can click on the image to see a larger view. Sorry, none of my images will fill your screen. And some of the images might take a few seconds to download.
Now, be aware that the presentation of images is likely to change. But the concept will remain - click on smaller images to see bigger ones. Use your back button to take you "back" to the page with small images unless they are already at the top of the page. In that case you can hit one of the scroll arrows (right or left of the images) to move the next images (to the right or left) into view.
To go to another page of images click on the one of the buttons at the top and bottom of a page.
In some formats, when you roll your cursor over the thumbnail image, a description will appear on your screen. In other cases the description will be present all the time.
Now select one of the sets of images and take a look.