They're 150 metres underground, the equivalent of 600 olympic-sized swimming pools and can store 1.47 million cubic metres of liquid hydrocarbons such as crude oil.<br/> <br />These storage caverns, which have been built under Jurong island in Singapore, are part of the island nations attempts to free up space.<br/> <br />With a land mass that's less than a third of the size of one of Europe's smallest countries, Luxembourg, but with more than ten times the population, in Singapore space comes at a premium says the Prime Minister, Lee Hsien Loong.<br/> <br />(SOUNDBITE) (English) SINGAPORE PRIME MINISTER LEE HSIEN LOONG SAYING:<br/> <br />"Singapore's land constraint is a little bit like peak oil. It exists, there is a theoretical limit, but with ingenuity and determination and technology, that limit can be quite a way off yet, and as you approach it, hopefully we can push it further off into the future<br/> <br />It took six years to build the $1.7 billion caverns<br/> <br />One of the company's Directors, Teo Tio
