According to the Guinness Book of World Records, ukulele is the easiest instrument to learn.
Gary Horsman
11

Thanks for your comment Gary, and for your good wishes! I chose the ukulele in part because I knew it was easy to learn… I wanted something I would make fairly rapid progress, since I didn’t have much time to devote to my learning. I would love to try to learn some other instrument, once I’ve really broken the back of the ukulele. Best wishes to you with your continuing musical explorations.