From BBC Earth Youtube page:
Phillipe Coustaeau and the team dive in the Red Sea, one of the warmest seas in the world. Despite the warm temperatures, coral reefs flourish with their flourescent pigmentation putting on an amazing show of technicolour. Fantastic clip taken from the BBC Oceans series. Visit http://www.bbcearth.com for all the latest animal news and wildlife videos and watch more high quality videos on the new BBC Earth YouTube channel here: http://www.youtube.com/bbcearth
Hat tip to Chris M!