The Endless Summer Surfing Challenge is already included in The Endless Summer Search For Surf. No need to buy it if you already have Search For Surf.
The Endless Summer Surfing Challenge has 12 single player challenge rounds and two player contest.
Learn to surf, complete the challenges, try all the players and the POV camera and have two player contests with a friend.
A Gentle Surfing Game "The Endless Summer Surfing Challenge"
Source: Steam Community (opens in a new tab)