4K HD Wallpaper: Undersea Creatures
Actually, the "creatures" are from aquarium and can be downloaded from here to be set on desktop backgrounds and homescreen phone. The 4K image was made by talented Amit Patel and from his courtesy the photo is available under CC By license.
Widescreen Desktop / Macbook (Retina): 2880x1800 (fits on: 2560x1600, 1920x1200, 1440x900)
High Definition HD 1080p: 1920x1080 (fits on: 1600x900, 1366x768, 1280x720)
Samsung Galaxy Tab & iPad: 2048x2048 (compatible with many tablets)
HTC, Samsung Galaxy & iPhone: 1080x1920 (compatible with many phones)