The alternative would be land-based storage tanks. They also cost money.<p>This happens sometimes. Example: <a href="http:&#x2F;&#x2F;www.telegraph.co.uk&#x2F;motoring&#x2F;news&#x2F;6601779&#x2F;Oil-tankers-parked-off-British-coast-as-speculators-wait-for-prices-to-rise.html" rel="nofollow">http:&#x2F;&#x2F;www.telegraph.co.uk&#x2F;motoring&#x2F;news&#x2F;6601779&#x2F;Oil-tankers...</a>