Measures of performance are used to quantify the ability of an individual to execute specific activities. In lizards, sprint speed is the most commonly evaluated measure of performance due to its relationship with biological fitness, presumably via increased effectiveness of foraging and escaping predators. Some lizards also use the aquatic environment and dive underwater as an effective means of foraging and/or escaping predators. We tested the usefulness of diving as a measure of performance in a small, diurnal lizard that frequently dives into intertidal water. Adults of Oligosoma smithi were encouraged to dive and the maximal duration of their dive as well as their behavior were recorded. Eighty-three percent of the 46 individuals dove in the six trials, with the longest dive time recorded at 6 min 36 s in a pregnant female. The diving ability of O. smithi was not related to pregnancy, whether an individual had eaten, or any of the morphological measures taken. We also searched for records of duration of diving in other lizards as a means of determining whether diving in water is widespread. Few data are available on duration of diving for other lizards. Our data suggest that, for species that submerge in water to forage and/or escape predators, diving ability should be considered as a measure of overall performance.