The technical problems of estimating the topographic height of a mangrove species or community are discussed. Transects normal to the seaward mangrove face were taken around the coast of Australia. They confirm that a stable margin will be approximately at mean sea level but that erosion, accretion or other disturbance may cause variation of the order of ±1 m. Studies in four species-rich rivers in north Queensland show that (i) there are marked distributional differences with respect to topographic height between long and short river estuaries, these differences being attributable to different tidal patterns; and (ii) there appear to be two mangrove types: the frontal species are tolerant of inundation, poorly adapted to emersion, whereas the upstream species behave as dry-land plants tolerant of only limited inundation. The topographic height range of individual plants of a single species may be almost 4 m, so that observations on individual plants are of little value.