Rating is available when the video has been rented.
This feature is not available right now. Please try again later.
Published on Jan 6, 2014
Subscribe to BBC News www.youtube.com/bbcnews Statistics suggest treacherous Australian ocean currents kill more people every year than all of those combined. They're known as riptides. They sweep people hundreds of metres away from the shore in just seconds. Now new techniques are being used to identify the danger - as Phil Mercer reports.