The Vandal Theory

One of the simplest explanations of the Vault activity is human vandals breaking into the Vault, moving the coffins around, and leaving undetected.
Pros: Colonel Chase supposedly did not have a shortage of enemies on the island, and some of them may have literally followed him to the grave. Slave laborers working in or around the cemetary may have found it easy to access the area around the tomb without drawing too much attention to themselves. The marble seal and coffins, while heavy, could conceivably have been moved by four or five men working together.
Cons: The Vault has a very small interior, making it difficult to move six heavy coffins around into different positions. The integrity of the impressions in the mortar seal and the sand on the floor over the period from the burial of Thomasina Clarke to the final reopening virtually precludes any tampering with the door. The Christ Church cemetery is easily visible from surrounding areas, making an unobserved intrusion unlikely. The massive public attention focused on the Vault after 1816 would have made it difficult for anyone to tamper with it unseen.

Visitor's comments:
"I really don't think that vandals had anything to do with it. The mortar was intact with the governor's seal still on it when it was reopened."

The Flood Theory

Some have proposed that the coffins were moved around after floating on water that somehow flooded the Vault.
Pros: A reasonable method for movement; lead coffins will float.
Cons: The Vault is a good 100 feet above sea level. No signs of water were detected.

Visitor's comments:
"I'm still partial to the flooding theory. I believe coral is porous so perhaps the flooding was caused by rain flooding, more than enough time to dry."

"Flooding, definetely. Limestone is porous. Groundwater could seep in, especially during tropical storms, not uncommon to Barbados."

The Earthquake / Volcano Theory

The coffins were buffeted by a seismic tremor.
Pros:Another reasonable method for movement. Barbados is located on a fault line, and many neighboring islands were formed by volcanic activity.
Cons: Barbados itself was formed from a coral uprising, not a volcano. Earthquakes would likely have been noticed by the locals. None of the other crypts in the area exhibited similar kinetic activity.

The Magnetic Force Theory

A magnetic-like force somewhere in the immediate area of the Chase Vault caused the coffins to move in response to it. Proposed by Eric Frank Russell in his Great World Mysteries (1957).

Pros: Based on the compilation diagram (shown in the history section), the coffins appear to have rotated around a central axis, some more than others, "spun around by some force gravitational, gyroscopic, electromagnetic, or goodness knows what." --Russell
Cons: Lead is not affected by ordinary magnetic forces. Wood isn't at all, of course, so it would be difficult to explain the movement of Mrs. Goddard's wooden coffin.

Visitor's comments:
"If there was a magnetic force strong enough to lift a dead body, wouldn't people notice other things moving?"

"Magnetic forces seem to be the best explaination. It seems that such a thing could easily be tested w/ today's technology."

"Magnetic Forces!! A wonderfully psuedo-scientific answer. Unfortunately, magnetic forces don't affect lead or wood. Good try though."

The Gas Theory

Gas from the decomposing bodies escaped so violently as to move the coffins around.
Pros: An interesting proposition.
Cons: Highly unlikely that such a force could be produced from escaping gases, especially on repeat instances.

Visitor's comments:
"How in God's great name could that many people think that a dead bodies escaping gases could move a lead coffin around a frikin room."

Supernatural Theories

Sir Arthur Conan Doyle, author of the Sherlock Holmes stories, suggested that the Chase Vault coffins were moved by less earthly forces. He is quoted as attributing the movements to the fact that bodies inside leaden coffins decompose more slowly than bodies in wooden ones. Doyle also has been said to believe that there is a certain "energy" inside the bodies of the youthfully deceased (i.e. Mary Anna Maria Chase, Samuel Brewster Ames, Dorcas Chase) that could somehow posthumously produce the kinetic activity seen inside the vault.
Others have suggested that the source of the disturbances arose from the tension between Dorcas Chase and her father, Colonel Thomas Chase, a tension that continued beyond their deaths.
Others have claimed the tension was actually between Mrs. Thomasina Goddard, the first occupant of the Vault, and the Chases who were later interred there.