The data represent 3 replicate measures of linear distance along 30 fixed transects on permanent subtidal monitoring sites around San Nicolas Island, CA. There were six sites, each of which had five 10-meter by 2-meter band transects on which a suite of kelps and macroinvertebrates was repeatedly counted over almost four decades. Although the transects are each approximately 10 m long, as measured with a meter tape extended between start and end eyebolts set in the sea floor, crevices, boulders, and reef structure provide much more than 20 square meters of surface area. In an effort to quantify the differences in rugosity between the transects, a 13 cm-circumference electronic surveyor’s wheel was used to measure the linear relief of each transect. Three replicate measurements were made per transect: down the lengthwise center and 1m away on each side of the center.