Environmental activists around the world have taken a stand against fracking – the controversial practice of injecting high-pressure water and industrial chemicals deep into the Earth to extract natural gas. While fracking does produce a large amount of natural gas, it has serious environmental impacts. Fracking causes increased seismic activity (earthquakes), uses very large amounts of water and is known to contaminate groundwater and soil.

As fracking takes center stage as one of the modern world’s biggest environmental issues, filmmakers have begun raising awareness by creating documentaries to explore its true impact. Here are four must-see documentaries about the fracking industry that will help you to understand this divisive topic better.

Gasland & Gasland Part II

With deadpan narration and stark visuals, filmmaker Josh Fox explores the impacts of fracking on landowners in these two critically-acclaimed documentaries. Gasland, which was nominated for the Best Documentary Oscar in 2011, begins with Fox receiving a request from an oil company to lease his land for drilling in exchange for oil and gas royalties. He then embarks on a cross-country journey to meet with people from all walks of life who have one thing in common: they live near fracking sites.

The real effects of fracking on individuals and communities are shown with a shocking straightforwardness. Also on display are the tactics used by oil companies to stymie the efforts of activists to expose the truth. Effective and eyeopening, Gasland is one of the most important environmental documentaries of the century, as is its sequel, Gasland Part II.

The Price of Sand: Silica Mines, Small Towns, and Money

An often-overlooked aspect of fracking is the use of sand in the drilling process. Such high amounts of sand are required that new silica mines are opening at a rapid rate, particularly in the states of Minnesota and Wisconsin.

The Price of Sand: Silica Mines, Small Towns, and Money examines the silica mining boom and the unexpected consequences it has had on the small communities surrounding the mines. Filmmaker Jim Tittle presents both sides of the frac-sand mining story but focuses mainly on the health impacts of the mines, which release microscopic silica dust, and on the misleading monetary promises made by the oil companies to local landowners.

Unearthed

South African filmmaker Jolynn Minnaar traveled the world to compile Unearthed, amassing over 300 interviews across South Africa, the United Kingdom, Canada and the United States. The result is an explosive investigative documentary that required Minnaar to undertake 18 months of research and experience many real dangers, including legal threats and exposure to fracking chemicals.

The film follows Minnaar as she attempts to uncover the truth about fracking, spurred on by the possibility of her hometown becoming a drilling site. She examines the claims of safety made by oil companies and calls into question the prioritization of natural gas over more sustainable, renewable energy sources. Along with her journey, she conducts revealing, often emotional interviews with a variety of people ranging from professors to scientists to average citizens living near pipelines and drilling sites.