A sunset, especially at sea, can be an amazing color spectacle. The hues will depend heavily on the weather, though — but you can push them a bit with a gradient map. Click on the “New Fill/Adjustment Layer” button in the Layer palette and select “Gradient Map” from the list. Click on the gradient to open the “Gradient Editor.
Click on the first color patch below the gradient, and change the color to red. Set the color patch on the opposite side to yellow, and click “OK.” Set the blending mode to “Soft Light” and reduce the opacity to about 50%. This will create a warm, almost golden sunset. Roughly select the area around the mouth with the Polygon Lasso tool. Go to Select → Modify → Feather, and enter a radius of 10 pixels.
Confirm, then click on Layer → New → Layer via Copy (or press Control/Command + J), then Edit → Puppet Warp. Photoshop will put a mesh over the entire layer in the shape of your previous selection. You can control the size of the mesh with the “Expansion” value in the Options bar.
Increase the density to “More Points” for increased precision. Press Control/Command + H to hide the mesh, then set the first pins to the corners of the mouth. Add more pins to distinctive spots of the mouth. By clicking and dragging the mesh, you can shape a nice smile. Macro shots of water drops are appealing, and shapes can be further accentuated with discreet coloring.
You could treat the bland surface with a linear gradient from #772222 (RGB 119, 34, 34) to #3333bb (RGB 51, 51, 187). If the photo is on a layer of its own, click on Layer → Layer Style → Gradient Overlay or double-click the layer next to its name.