Gerrids stand on the water film rather than floating in it. Their legs are covered in dense hydrophobic microhairs, each finely grooved, which trap air and prevent the leg from breaking the surface. The middle legs row in a sculling stroke, and the animal can support many times its own weight before the film gives way.
Five Halobates species have taken that ability offshore. They live permanently on open tropical seas, never touch land, and have no wings. Because they need something solid on which to lay, they use whatever floats: feathers, pumice, seabird carcasses and, increasingly, plastic fragments, which has made their egg densities a subject of marine debris research.
The usual explanation for insects being scarce at sea is not salt but competition and the difficulty of the surface habitat. Halobates shows the barrier can be crossed, and that the crossing has happened remarkably few times.