Player Embed Code: <iframe width='500' height='300' scrolling='no' frameborder='0' style='border: none; overflow: hidden; width: 500px; height: 300px;' allowtransparency='true' src='https://www.dvidshub.net/video/embed/285889'></iframe> Download Embed Share Sink or Swim: Becoming a Marine Corps Instructor of Water Survival Defense Media Activity - Marines April 3, 2013 | 2:08 The Marine Corps Instructor of Water Survival Course is among the most physically demanding courses in the Corps. The attrition rate can range from 20 to 50 percent, but students who endure earn the title of MCIWS.Less than 600 Marines in the Corps hold the title of Marine Corps Instructor of Water Survival. The three-week MCIWS course creates instructors who can train Marines to react and survive life-threatening situations in the water.For a photo walkthrough of the course visit:http://www.flickr.com/photos/marinessocialmedia/sets/72157633049682553/show/