I am thinking about taking up surfing. It seems difficult though
A surface water sport like surfing will always be difficult unless you practice everyday 
Who even thought up such a sport?
The native peoples of the Pacific many thousands of year ago, when they first embarked on sea.
Is it a competative sport or in the Olympics?
It can be, in Olympics there are surfing competitions that include knee boarding, and surf matting
What is surf matting?
boarding, when a surfer rides a wave on a bodyboard, either lying on their belly, drop knee, or sometimes even standing up on a body board. Other types of surfing include knee boarding, surf matting (riding inflatable mats), and using foils. Body surfing, where the wave is surfed without a board, using the surfer's own body to catch and ride the wave, is very common and is considered by some to be the purest form of surfing.
Three major subdivisions within stand-up
such as whale watching and coastal birdwatching.
Humans enjoy venturing into the sea; children paddle and splash in the shallows and many people take pleasure in bathing and relaxing on the beach. This was not always the case, with sea bathing becoming the vogue in Europe in the 18th century after Dr. William Buchan advocated the practice for health reasons. Surfing is a sport in which a wave is ridden by a surfer, with or without a surfboard. Other marine water sports include kite surfing, where a power kite propels a