Stand up Paddle Boarding, fondly called SUP by those "in the know" involves standing on a long board, very similar to a surfboard, and using a paddle propelling the rider across the top of the water. Board length, size, weight, construction materials and purposes are as varied as the people who paddle them!
There is some debate about the first historic recording of stand up paddling. Some sources claim thousands of years ago in Peru, ancient people first created vessels they stood on and paddled while fishing. Other sources claim the first recorded stand up boarders were African warriors in ancient times. Still others claim the 17th century gondoliers in Venice who used paddles while standing to propel their vessels through the canals as the originals.
Wherever standing on a vessel and using a paddle was first devised, most agree that stand up paddle boarding for fun originated in Hawaii sometime in the 1940's. Surfers took canoe paddles out into the waters to make their surfing easier. Today, SUPing is a hugely popular sport all around the world.
Yoga originated in India over 5000 years ago and has gained popularity in the United States within the last hundred years. Yoga practitioners or "yogi's" constantly strive for balance in their postures and life.
Combining SUP and Yoga was a natural progression! I searched the internet for the origins of SUP yoga, but have not yet found an origin! Personally, when I saw a flier for a class a couple years ago, I was already regularly on the water on my paddle board, and a regularly practicing yogi. I did my first class and was hooked!
SUP Yoga typically involves a combination of Hatha (slow holding) and Vinyasa (flowing) poses. The combination of being on the water and flowing through poses requires mindful engagement of muscles; otherwise you end up "diving in asana".