MH370 debris
Photograph taken Dec. 23, 2015, showing Part No. 3 significantly colonized by barnacles. ATSB/Schalk Lückhoff

Malaysian Airlines Flight 370 disappeared from radar three years ago Wednesday, setting off the most perplexing aviation mystery of the century, a mystery that has spawned an overwhelming number of conspiracy theories attempting to explain what happened to the 239 people aboard the doomed flight.

Even after Malaysian Prime Minister Najib Razak said that investigators had "conclusively confirmed" debris found on the Indian Ocean island of Réunion in 2015 was part of the missing flight, family members of the flight's passengers and conspiracy theorists alike continued to search for explanations, a search fueled by the fact that the Australian Transport Safety Bureau suspended its hunt for the plane in January.

Below are some of the most notable conspiracy theories that have attempted to explain what happened to MH370.

Diego Garcia

One of the most popular conspiracy theories holds the plane was flown to the U.S. Navy base on the British-owned island of Diego Garcia in the Indian Ocean. The military base has the perfect mixture of remote location and clandestine associations to fuel conspiracy theories. In 2015, former Secretary of State Colin Powell's chief of staff told Vice News a CIA black site was run on the island as "a transit site where people were temporarily housed, let us say, and interrogated from time to time."

Freelance journalist Jim Stone has claimed to have found evidence an IBM employee named Philip Woods, who was on the flight managed to send a text message with an attached black picture that contained data that showed the message was sent from Diego Garcia after the flight supposedly crashed. The accompanying text with the picture allegedly said:

"I have been held hostage by unknown military personnel after my flight was hijacked [blindfolded]. I work for IBM and I have managed to hide my cellphone in my ass during the hijack. I have been separated from the rest of the passengers and I am in a cell. My name is Philip Wood. I think I have been drugged as well and cannot think clearly."

Shot Down

Multiple theories argue the plane was shot down by military forces.

One theory is that the U.S. shot down the plane because it had been hijacked and the hijackers were planning on crashing the plane into the military base on Diego Garcia.

Another theory says the plane was accidentally shot down during a joint U.S.-Thai military exercise.

A third theory suggests North Korea shot down the plane. Just 10 days before MH370 went missing, South Korea claimed North Korea fired projectiles off its coast at nearly the same time a China Southern Airlines flight was passing through the area.

North Korea

Relations have been tense between North Korea and Malaysia since the alleged assassination of North Korean dictator Kim Jong Un's half-brother in the Kuala Lumpur airport. The theory that North Korea is behind the plane's disappearance has gained traction since Kim Jong Nam's killing, which shows both how brazen North Korea's ruler is — it appears he sent assassins into a foreign country with a weapon of mass destruction — and how North Korea has mastered Malaysian airport security. Some have suggested North Korea wanted the plane for its technology.

Russia

After a Malaysian Airlines Flight 17 was shot down over Ukraine, probably by pro-Russian forces, just a few months after MH370 disappeared, conspiracy theories about Russian involvement quickly proliferated. One that gained traction was the theory that MH17 was actually MH370.

Pilot Murder-Suicide

Former Australian Prime Minister Tony Abbott has said the plane's fate was most likely decided by the flight's captain, Zaharie Ahmad Shah.

"I have always said the most plausible scenario was murder-suicide and if this guy wanted to create the world's greatest mystery why wouldn't he have piloted the thing to the very end and gone further south?" Abbot told an Australian newspaper.

In 2016, New York Magazine reported Shah had performed a simulated flight on his extensive home-built flight simulator that mirrored MH370's known flight path and ended with a crash in the Indian Ocean.

Aliens

There's really nothing to explain here. Some people think it was aliens.

Black Holes

During its coverage of the disappearance of flight MH370, CNN entertained the possibility that the plane was eaten by a black hole, only to assure viewers that the plane was probably not eaten by a black hole.