Adult males alighted on the open water surface midstream in a shallow river in the Cape Province, South Africa. They remained on the water surface for up to a few min, sailing against the current upstream in the wind. The behaviour apparently was associated neither with mating nor feeding. The open water surface appears to be a relatively safe place to rest when mid-stream perches arc in short supply. Such a resting spot is away from predators of the marginal vegetation, such as frogs and large Odonata. There is possibly relatively low risk from birds. Predation from fish is also unlikely. It is tentatively concluded that the water surface is a thin layer of relatively enemy-free space where risks from predation are less than at other microsites.