So here we have an image which captures a lot of the elements of a wide-angle lens that you can use to your advantage.
Remember that things close to the camera are big, things away from the camera are small. Another way of saying that is when you get up close to something it looks big, while things in the background will look small.
When you put a tiny little turtle in the corner of the frame and there is a huge expanse of beach surrounding the little flippery adventurer, they look even tinier. Even though it is still the closest thing to the camera it actually looks quite small because I'm not all that close to it. If you get too close the turtle would look much bigger than it is and you would lose that sense of the tiny little battler against the elements.
Remember that when you're using the wide-angle the foreground becomes the most important part of the picture. By having the turtle in the bottom foreground of the picture you can emphasise the foreground, middle ground, background 3D look we've been talking about.
Because the wide-angle lens opens up the perspective the ocean looks quite a long way away, giving a sense of the effort involved in reaching it. If I had gone with a really wide lens, however, the ocean would have looked even farther away but the turtle would have been a pin prick in the middle of the frame. It's always a balancing act.
Wide-angle lenses inherently have a pretty large depth-of-field. What that means is that the ocean in the background isn't such a big blur that you can't tell what it is, which is very important in the telling of the story.
If I had gone with a telephoto lens then the turtle would have looked big and the ocean very close which was the total opposite of what I wanted to express with this photo - namely that of the tiny little battler against the elements trying to make its way to the far off ocean.
A great way to instinctively know what lens you should use is to try walking around for a whole day photographing with just one lens. If you're using a zoom lens try taping the zoom ring so it doesn't move. Set it on a particular setting and leave it there and just practice using that one focal length of lens. Before you know it you'll know exactly what a photo taken with that lens will look like before you even look through the viewfinder.