-My initial sketch ended up looking fairly similar to what I finished with, only really changing the angle of the water and the positioning of some of the text.
-I started with a picture of the sky, which already had a nice directional light source. I flipped it, duplicated it, mirrored it, and layered the two of them on top of each other to get a full skybox.
-I then masked out a picture of a lake to the shape I needed, then copied, darkened, and moved the copy to act as a background for the waterfall.
-Next, I masked out part of a waterfall, and patched it along the edge of the water.
-The "door" is just a simple white rectangle with an outer glow applied.
-I masked out a picture of clouds taken from an aerial viewpoint and arranged them to surround the water.
-I then masked out a picture of a boat and scaled it to size, then did the same with the guy on the boat.
-To create the reflection: I duplicated the guy and the boat, merged them into one layer, flipped them vertically, moved them into position, lowered the opacity, then added a perspective warp and motion blur.
-I added the ripples to the water by making an elliptical selection of the area around the boat, duplicating it, and applying a Filter > Distort > Ripple. I laid the ripples back on top of their original location, and smudged and blended the water back together.
-Finally, I masked out some birds and threw them in the background.
-The font used for the title and tagline is Avenir.