On 21 August, 2009 the Montara oil rig suffered a blowout and began spilling oil into the ocean. The well was located in 250 ft of water, between East Timor and Australia. Even though this rig was in relatively shallow water, it still took four attempts over ten weeks to block the leak.

The attempts eventually succeeded when mud was pumped into a relief well 74 days after the blowout.  The Department of Resources, Energy and Tourism estimated that up to 2,000 barrels per day (or up to 85,000 gallons) were spilled over that time, five times the estimate given by the PTT Exploration & Production Public Company Limited.  In the end, the Wilderness Society estimated the oil slick to have affected 19,000 square miles of ocean.

After assessing this area, the federal Environmental Minister and WWF Australia released reports confirming that a large number of whales, dolphins, and sea turtles were feeding in these polluted waters and noting the presence of dying birds and dead sea snakes. Endangered flat back and threatened hawksbill turtles were observed swimming in the slick. Birds were of particular concern as many were breeding in nearby reserves and migrating across the slick, to get away from the northern winter. The oil sheen also attracted fish, which, in turn, attracted feeding birds. The Australian Government treated a small number of birds, including common noddies and brown boobies.

Fishermen in Indonesia reported that the oil that had reached Indonesian waters was making them ill, killing the fish and damaging thousands of acres of valuable and ready-to-harvest seaweed.  Seaweed is a valuable commodity for food as well as other uses such as cosmetics, fertilizer and biofuel.

The Montara oil spill story demonstrates that offshore drilling, even in shallow water, is not safe, and can lead to severe impacts on ecosystems and local economies.