Japan's legal killings of whales and dolphins has drawn the ire of environmental groups for years. But now a new film, using some clandestine camera technology, has documented the killing in graphic detail for the world at large.

The Cove, a new documentary, tracks the dolphin killings in Taiji, Japan. The area harvests dolphins to sell both live to aquatic attractions and also as meat. The whole area is fenced off; the filmmakers had to break the law and get creative to get capture their footage, including using aerial drones and phony rocks with cameras inside.

The Japanese government acknowledges that its fishermen slaughter about 23,000 dolphins each year, but the killing is legal there and government officials argue that eating dolphin meat is a cultural tradition. The country has gotten plenty of heat over its widespread whaling, too, though the government maintains that whale killing is done in the same of scientific research.

Last year Japan revealed that its scientific whaling program had killed 4,500 whales, though American scientists argued that the same results could have been achieved by only giving the whales biopsies, and not killing them. Though Japan defends its right to both dolphin and whale killing in the name of science and tradition, it  certainly wants to shield both from bad publicity. The filmmakers behind The Cove were harassed, but still managed to get their grisly footage of the waters stained red with blood.