This article examines the effectiveness of using a knife as a means of protection from a shark attack while swimming. It is suggested that, while a knife can be used as a deterrent to scare off any shark, it is not a reliable form of protection as the chances of actually succeeding in injuring a shark with a knife are slim. Furthermore, this type of action may actually put the swimmer in more danger and put them at risk of being attacked. The article concludes that the best way to avoid a shark attack is to be aware of the warning signs and to avoid swimming in areas known to be inhabited by sharks.