Some of the common theories of the triangle are as follows.

Electromagnetic anomalies - which can cause compasses to go haywire and equipment to cease function, one theory this may happen by a lack of magnetic declination near 80 degrees west (off coast of Miami) and the agonic line is one of two points on the Earth's surface where compasses point directly to the north pole which can make navigation with a compass difficult, but this cannot explain most of the disappearances.  The Hutchison Effect however could explain how these "vapor clouds" could form out of nowhere causing these electromagnetic anomalies to start.  

The Hutchison Effect - Vancouver scientist John Hutchison developed these theories through experiments.  He started by studying longitudinal wavelengths of Tesla (Nikola Tesla, a radio pioneer) in 1979 which produced amazing affects such as objects made up of different materials (wood, plastic, copper) levitating caused by the wavelengths of the machines.  Objects would bend, catch on fire, and contort in weird ways.  Hutchison would be arrested and his equipment confiscated multiple times over the years and he was contacted by the U.S., Canada, and Japan for military work.  Another incident is where his neighbor called the cops on him because he was levitating in his own house.  Though his equipment has been tinkered with and changed over time, his experiments can create swirling clouds and lights, green glows and phosphorescence, and electromagnetic anomalies described in the triangle.  If someone like Hutchison can create these with such little power, mother nature could probably create these anomalies too which could explain the reasons aircrafts and ships disappear.  The Hutchison effect proves that nature has the power to perform amazing things.

Abnormal and sudden weather anomalies - freak weather is also described by those in the triangle, clouds forming out of thin air and jolts/pulses hitting their craft out of nowhere.  Severe storms could explain why a number of ships/aircraft could have disappeared and no wreckage is found, but what causes them and if they really are just storms is unknown.

Vortex or time warps - Some reports which include radio contact before the person disappears usually include the person describing themselves as being in a vortex like storm or portal which ultimately ends up in their disappearance.  The few that have made it out describe them as spawning out of clear skies with no warning signs.  These "holes in time" could explain some of the sudden loss of contact, and since black holes can exist in space, it may be possible that the Bermuda Triangle could be a place where these vortexes could be on Earth.

Methane gas pockets - Methane hydrates may be a source for the disappearances of ships, methane gas locked below the sea bed in the Bermuda Triangle which are released by subterranean landslides can reduce the density of the water and ultimately sink a ship.  This theory can explain but a fraction of the disappearances of ships, and planes can't be affected by this idea.

There are other theories as well, but many of them are highly unlikely, so the mystery of the devil's triangle still remains today.