International Surfing Day, held annually on or near the date of the summer solstice—usually June 21 (20 June on leap years)—is an unofficial, environmentally conscious sports-centered holiday that celebrates the sport of surfing and the surfing lifestyle and the sustainability of ocean resources. 

International Surfing Day was established in 2004 by Surfing Magazine and The Surfrider Foundation,  International Surfing Day closely follows the spirit and intent of the World Surf Day established by the Usenet newsgroup alt.surfing in 1993. International Surfing Day is a worldwide celebration of the sport of surfing. The day is observed with surf contests, barbecues, film screenings and other surf-related activities. Surfers also use the day to give back to the environment by organizing beach clean-ups, dune and other habitat restoration and other activities such as lobbying to maintain the recreation areas in California where surfing occurs, or Naupaka planting in Hawaii. -wikipedia

http://www.surfrider.org/press-center/entry/8th-annual-international-surfing-day-returns-june-20
 
 http://isd.surfrider.org/