Royal Dutch Shell and ConocoPhillips, among other companies, will end their exploration of the area, Bloomberg reported Tuesday.

The publication notes that this comes as crude oil prices have plummeted and after less than stellar results in their efforts so far in the region. The decision also came ahead of a May 1 deadline to pay the government millions of dollars in rent for their projects.

But the $2.5 billion was originally spent by the oil companies because of potential opportunity in the Arctic waters. In fact, it’s estimated that there are over 20 billion barrels worth of oil and 132 trillion cubic feet of natural gas in the region.

“Arctic exploration has been put back several years, given the low oil price environment, the significant cost involved in exploration and the environmental risks that it entails,” Peter Kiernan, an energy analyst at The Economist Intelligence Unit, to Bloomberg.