Abstract: An altimeter device employs a solid state pressure sensor having a strain-sensitive element directly in a silicon diaphragm, which is connected at one side to a closed vacuum chamber. The entire device is very compact and may be in the form of a wristwatch. A display indicates altitude or relative altitude above or below a reference point to the user, and electronics associated with the device provide for accumulation of vertical change in one direction, regardless of intervening changes in the opposite direction. In this way, a skier, hiker or biker, for example, may determine total vertical drop or vertical rise encountered in a selected period, without regard to offset from movements in the opposite direction. At the same time, the user may also determine his altitude at any given point, and in a preferred form the altimeter device includes a clock and a time-averaging feature, for calculating and displaying rate of climb or descent, both instantaneous and average over a selected interval.