The present invention relates to improved explosives. More particularly, the invention relates to cap-sensitive slurry explosives, either water-in-oil emulsion explosives or conventional water-based slurries having a continuous aqueous phase, containing high strength, small, hollow, dispersed spheres as a density reducing agent. The preferred explosive is a cap-sensitive water-in-oil emulsion explosive having a water-immiscible liquid organic fuel as a continuous phase; an emulsified aqueous inorganic oxidizer salt solution as a discontinuous phase; an emulsifier; and as a density reducing agent, small, hollow, dispersed spheres, preferably glass or plastic, having a strength such that a maximum of about 10% collapse under a pressure of 500 psi. As used herein, the term "cap-sensitive" means that the explosive composition is detonable with a No. 8 cap at 20.degree. C. in a charge diameter of 32 mm or less.