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.

These storage caverns, which have been built under Jurong island in Singapore, are part of the island nations attempts to free up space.

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.

(SOUNDBITE) (English) SINGAPORE PRIME MINISTER LEE HSIEN LOONG SAYING:

"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

It took six years to build the $1.7 billion caverns

One of the company's Directors, Teo Tio