I like the methane hydrates theory.
Loss or water and air craft in the "triangle" is theorized to occur due to pockets of methane gas. The gas builds up due to the decomposition of organic materials on and below the ocean floor or from large natural occurring pockets deep within the earth. When the gas is released it causes giant methane clouds that bubble up through the water. When a ship goes through this methane bubble field the displacement of the ship is affected and the ship can sink. When the gas goes into the atmosphere (methane is lighter than air) it can cause an airplanes engines to stall, it will also cause a loss of lift due to methane being thinner than air. The methane can also render humans unconscious and the plane will crash due to multiple issues. Most plane crashes in the triangle are low altitude piston engine types without a pressurized cabin so the methane will affect them far worse than a high altitude jet aircraft that will not be affected because of a pressurized cabin, turbine engine and the gas being dispersed at a higher altitude.
The other theory is people cannot read airplane instrumentation correctly because they are stupid idiots. They crash because a human being is in the equation. Same goes for boats, the human factor.