Determining the cause of the explosion was fiercely opionated. With several different accusations and perspectives on the loss of men, the answer was decided for America. On March 28, 1898, the United States Naval Court of Inquiry found that the Maine was destroyed by a submerged mine. Although there was no direct blame, the implication on the Spanish was clear.
By 1976, the case of the USS Maine was reopened by Admiral Hyman G. Rickover who believed modern science was the answer. After consultations of experts and reexamining documents from the first investigation, it was concluded that the damage caused was inconsistent of that of a mine. Rickover claims is was most likely a coal dust fire. Even today, his findings have been disputed and there has been no final solution as to what caused the explosion of the Maine.
Sources: http://en.wikipedia.org/wiki/USS_Maine_(ACR-1)
www.pbs.org/crucible/tl10.html