The huge wave image used as the default wallpaper for OS X Mavericks is certainly striking, but if you don't harbor any particular affinity toward surfing, or the ocean in general, you have other options. OS X has some options readily available on the Desktop wallpaper screen in System Preferences, but you'll notice there are different images available on its Screen Saver page, where it lists four Default Collections: National Geographic, aerial, cosmos, and nature patterns.
Count the images and you'll see there are 43 images across those four screensaver collections. You can use these images as your desktop image by locating them and dragging them one at a time into the Desktop page in System Preferences.
To track them down, hit Command-Shift-G from your desktop to open the Finder's Go to Folder window. Next, enter this path:
/Library/Screen Savers/Default Collections/
Browse through the folders and then drag an image into the Desktop window of System Preferences.