Incredible videos: mussel hunting under ice during low tide, others
http://www.youtube.com/watch_popup?v=Z0qGvC3vqaA
Amazing pendulum waves of Mach:
http://sciencedemonstrations.fas.harvard.edu/icb/icb.do?keyword=k16940&pageid=icb.page80863&pageContentId=icb.pagecontent341734&state=maximize&view=view.do&viewParam_name=indepth.html#a_icb_pagecontent341734
