One year ago, an explosion rocked the Deepwater Horizon drilling rig in the Gulf of Mexico, killing 11 workers, sinking the rig, and releasing a massive amount of crude oil into the ocean. Nearly 4.9 million barrels of oil (200 million gallons) are believed to have leaked into the Gulf, fouling shorelines, crushing local economies, and damaging the environment to an extent that's yet to be fully determined. Studies are ongoing, focused on issues such as dispersant effectiveness and long-term health effects on humans and animals -- and litigation is ongoing, with more than 300 related lawsuits recently consolidated for a trial, beginning in February 2012, that will assign fault in terms of percentages to BP and other companies. Now, one year later, discovering the full extent of the disaster remains difficult, hampered by the scale of the affected area, the volume of the oil and differing explanations of what happened to the bulk of it, and criminal and civil litigation. These images give both a look back and a current view of the area affected by the largest accidental oil spill in history.