The invention is a means to vibrate and/or rhythmically deform various devices for massage and/or sexual stimulation, and the devices themselves, comprising at least two, and normally three elements: (1) one or more hydraulically driven oscillators within a massage and/or sexual stimulation device; (2) a hydraulic actuator to move hydraulic fluid into and out of the device (1) (3) optionally, a flexible hose or hoses connected at one end to the sexual stimulation device or devices and at the other end to the hydraulic actuator. The particular devices actuated by the present invention include various massage and/or sexual stimulation devices, including muscle massagers, dildos, and penis rings (with or without attachment to secondary anal stimulators), sexually stimulating underwear, and two-ended dildos intended to anchor on one end (the wearer's end) in the wearer's vagina and optionally also in the wearer's anus, for example. For purposes of this disclosure, “sexually stimulating devices” and other similar language should also be understood to include massage devices that are not specifically intended for sexual stimulation. Compared to prior art vibrating sexual stimulators, the devices of this invention are capable of more complex modes of motion and both higher amplitude and slower deformation rates. The hydraulically actuated sexual stimulators of this invention are powerful, compact, quiet, and have low rates of heat generation compared to prior art electrically-driven vibrating sexual stimulation devices. In addition, said devices can be conveniently heated or cooled via the hydraulic fluid.