Not necessarily. Note that you take precautions because you foresee difficulties. If you intend to go diving in shark-infested waters... or, indeed, any body of water that might conceivably host sharks... then considering that fact in advance, purchasing shark repellent, and having it on-hand during the dive is totally sensible. If you're going to the South Pole instead, then shark repellent is worse then useless; it's presence will serve merely as additional weight to hinder your progress. The difference is, as the quote suggests, a question of whethe... (read more)